diff --git a/changelog_entry.yaml b/changelog_entry.yaml
index e69de29bb2d..76ffeef0260 100644
--- a/changelog_entry.yaml
+++ b/changelog_entry.yaml
@@ -0,0 +1,4 @@
+- bump: patch
+  changes:
+    changed:
+      - Add historical values to Washington TANF parameters.
diff --git a/policyengine_us/parameters/gov/states/wa/dshs/tanf/income/deductions/earned_income_disregard/amount.yaml b/policyengine_us/parameters/gov/states/wa/dshs/tanf/income/deductions/earned_income_disregard/amount.yaml
index 23f0bf93201..df38faf03c1 100644
--- a/policyengine_us/parameters/gov/states/wa/dshs/tanf/income/deductions/earned_income_disregard/amount.yaml
+++ b/policyengine_us/parameters/gov/states/wa/dshs/tanf/income/deductions/earned_income_disregard/amount.yaml
@@ -1,7 +1,7 @@
 description: Washington deducts this amount from the household's total gross earned income under the Temporary Assistance for Needy Families program.
 
 values:
-  2024-01-01: 500
+  2024-08-01: 500
 
 metadata:
   unit: currency-USD
@@ -10,5 +10,5 @@ metadata:
   reference:
     - title: WAC 388-450-0170(2) - Deducting the first $500 of earned income
       href: https://app.leg.wa.gov/wac/default.aspx?cite=388-450-0170
-    - title: DSHS Eligibility A-Z Manual, Income - Earned Income Deductions
-      href: https://www.dshs.wa.gov/esa/income-table-contents/budgeting
+    - title: HB 1447 (2023 c 418) Sec 5
+      href: https://lawfilesext.leg.wa.gov/biennium/2023-24/Pdf/Bills/Session%20Laws/House/1447-S2.SL.pdf#page=10
diff --git a/policyengine_us/parameters/gov/states/wa/dshs/tanf/income/deductions/earned_income_disregard/in_effect.yaml b/policyengine_us/parameters/gov/states/wa/dshs/tanf/income/deductions/earned_income_disregard/in_effect.yaml
new file mode 100644
index 00000000000..3a7334a3009
--- /dev/null
+++ b/policyengine_us/parameters/gov/states/wa/dshs/tanf/income/deductions/earned_income_disregard/in_effect.yaml
@@ -0,0 +1,15 @@
+description: Washington applies a flat earnings disregard to earned income under the Temporary Assistance for Needy Families program if this is true.
+
+values:
+  1998-09-01: false
+  2024-08-01: true
+
+metadata:
+  unit: bool
+  period: month
+  label: Washington TANF flat earnings disregard in effect
+  reference:
+    - title: WAC 388-450-0170 - Earned income deductions
+      href: https://app.leg.wa.gov/wac/default.aspx?cite=388-450-0170
+    - title: HB 1447 (2023 c 418) Sec 5
+      href: https://lawfilesext.leg.wa.gov/biennium/2023-24/Pdf/Bills/Session%20Laws/House/1447-S2.SL.pdf#page=10
diff --git a/policyengine_us/parameters/gov/states/wa/dshs/tanf/income/deductions/earned_income_disregard/percentage_disregarded.yaml b/policyengine_us/parameters/gov/states/wa/dshs/tanf/income/deductions/earned_income_disregard/rate.yaml
similarity index 70%
rename from policyengine_us/parameters/gov/states/wa/dshs/tanf/income/deductions/earned_income_disregard/percentage_disregarded.yaml
rename to policyengine_us/parameters/gov/states/wa/dshs/tanf/income/deductions/earned_income_disregard/rate.yaml
index f64669a0d19..6a7d649968f 100644
--- a/policyengine_us/parameters/gov/states/wa/dshs/tanf/income/deductions/earned_income_disregard/percentage_disregarded.yaml
+++ b/policyengine_us/parameters/gov/states/wa/dshs/tanf/income/deductions/earned_income_disregard/rate.yaml
@@ -1,7 +1,7 @@
 description: Washington disregards this share of remaining earned income under the Temporary Assistance for Needy Families program.
 
 values:
-  2024-01-01: 0.5
+  1998-09-01: 0.5
 
 metadata:
   unit: /1
@@ -10,5 +10,3 @@ metadata:
   reference:
     - title: WAC 388-450-0170(3) - Subtract 50% of remaining earned income
       href: https://app.leg.wa.gov/wac/default.aspx?cite=388-450-0170
-    - title: DSHS Eligibility A-Z Manual, Income - Earned Income Deductions
-      href: https://www.dshs.wa.gov/esa/income-table-contents/budgeting
diff --git a/policyengine_us/parameters/gov/states/wa/dshs/tanf/income/limit.yaml b/policyengine_us/parameters/gov/states/wa/dshs/tanf/income/limit.yaml
index bebbe4f2469..08e4ccc7d6f 100644
--- a/policyengine_us/parameters/gov/states/wa/dshs/tanf/income/limit.yaml
+++ b/policyengine_us/parameters/gov/states/wa/dshs/tanf/income/limit.yaml
@@ -1,8 +1,8 @@
 description: Washington sets these gross earned income limits for the Temporary Assistance for Needy Families program.
-# Note: These values follow the formula: Income Limit = (Payment Standard × 2) + $500
-# This represents the break-even point where countable income equals the payment standard,
-# resulting in $0 benefit. While mathematically derived, WAC 388-478-0035 publishes these
-# as a table rather than a formula, so we preserve the table structure here.
+# Note: These values appear to follow a mathematical relationship with payment standards
+# (Income Limit ≈ Payment Standard × 2, plus $500 after Aug 1, 2024), but no legal code
+# explicitly states this formula. WAC 388-478-0035 publishes these as a table.
+# Values here are taken directly from the published WSR tables.
 
 metadata:
   unit: currency-USD
@@ -10,29 +10,77 @@ metadata:
   label: Washington TANF maximum gross earned income limit
   breakdown:
     - range(1, 11)
-  breakdown_labels:
+  breakdown_label:
     - Assistance unit size
   reference:
     - title: WAC 388-478-0035 - Maximum earned income limits for TANF, SFA, PWA, and RCA
       href: https://app.leg.wa.gov/wac/default.aspx?cite=388-478-0035
+    - title: WAC 388-478-0035 Maximum earned income limits for TANF, SFA, PWA, and RCA. 2016
+      href: https://lawfilesext.leg.wa.gov/law/wsr/2016/01/16-01-093.htm
+    - title: WAC 388-478-0035 Maximum earned income limits for TANF, SFA, PWA, and RCA. 2018
+      href: https://lawfilesext.leg.wa.gov/law/wsr/2018/09/18-09-088.htm
+    - title: WAC 388-478-0035 Maximum earned income limits for TANF, SFA, PWA, and RCA. 2021
+      href: https://lawfilesext.leg.wa.gov/law/wsr/2021/21/21-21-054.htm
+    - title: WAC 388-478-0035 Maximum earned income limits for TANF, SFA, PWA, and RCA. 2024
+      href: https://lawfilesext.leg.wa.gov/law/wsr/2023/23/23-23-054.htm
 
 1:
-  2024-01-01: 1_400
+  2016-02-01: 665
+  2018-07-01: 726
+  2021-07-01: 834
+  2024-01-01: 900
+  2024-08-01: 1_400
 2:
-  2024-01-01: 1_640
+  2016-02-01: 839
+  2018-07-01: 918
+  2021-07-01: 1_056
+  2024-01-01: 1_140
+  2024-08-01: 1_640
 3:
-  2024-01-01: 1_912
+  2016-02-01: 1_042
+  2018-07-01: 1_138
+  2021-07-01: 1_308
+  2024-01-01: 1_412
+  2024-08-01: 1_912
 4:
-  2024-01-01: 2_166
+  2016-02-01: 1_225
+  2018-07-01: 1_340
+  2021-07-01: 1_542
+  2024-01-01: 1_666
+  2024-08-01: 2_166
 5:
-  2024-01-01: 2_418
+  2016-02-01: 1_413
+  2018-07-01: 1_544
+  2021-07-01: 1_776
+  2024-01-01: 1_918
+  2024-08-01: 2_418
 6:
-  2024-01-01: 2_680
+  2016-02-01: 1_604
+  2018-07-01: 1_754
+  2021-07-01: 2_018
+  2024-01-01: 2_180
+  2024-08-01: 2_680
 7:
-  2024-01-01: 3_016
+  2016-02-01: 1_853
+  2018-07-01: 2_026
+  2021-07-01: 2_330
+  2024-01-01: 2_516
+  2024-08-01: 3_016
 8:
-  2024-01-01: 3_284
+  2016-02-01: 2_051
+  2018-07-01: 2_242
+  2021-07-01: 2_578
+  2024-01-01: 2_784
+  2024-08-01: 3_284
 9:
-  2024-01-01: 3_558
+  2016-02-01: 2_252
+  2018-07-01: 2_462
+  2021-07-01: 2_832
+  2024-01-01: 3_058
+  2024-08-01: 3_558
 10:
-  2024-01-01: 3_824
+  2016-02-01: 2_448
+  2018-07-01: 2_676
+  2021-07-01: 3_078
+  2024-01-01: 3_324
+  2024-08-01: 3_824
diff --git a/policyengine_us/parameters/gov/states/wa/dshs/tanf/maximum_family_size.yaml b/policyengine_us/parameters/gov/states/wa/dshs/tanf/maximum_family_size.yaml
index 1524c9eee89..8a468bfb1f1 100644
--- a/policyengine_us/parameters/gov/states/wa/dshs/tanf/maximum_family_size.yaml
+++ b/policyengine_us/parameters/gov/states/wa/dshs/tanf/maximum_family_size.yaml
@@ -1,7 +1,7 @@
 description: Washington defines payment standards and income limits for family sizes up to this maximum under the Temporary Assistance for Needy Families program.
 
 values:
-  2024-01-01: 10
+  2016-01-01: 10
 
 metadata:
   unit: person
diff --git a/policyengine_us/parameters/gov/states/wa/dshs/tanf/payment_standard/amount.yaml b/policyengine_us/parameters/gov/states/wa/dshs/tanf/payment_standard/amount.yaml
index b2ab05695d9..9c524636efd 100644
--- a/policyengine_us/parameters/gov/states/wa/dshs/tanf/payment_standard/amount.yaml
+++ b/policyengine_us/parameters/gov/states/wa/dshs/tanf/payment_standard/amount.yaml
@@ -6,29 +6,68 @@ metadata:
   label: Washington TANF payment standard
   breakdown:
     - range(1, 11)
-  breakdown_labels:
+  breakdown_label:
     - Assistance unit size
   reference:
     - title: WAC 388-478-0020 - Payment standards for TANF, SFA, and RCA
       href: https://app.leg.wa.gov/wac/default.aspx?cite=388-478-0020
+    - title: WAC 388-478-0020 Payment standards for TANF, SFA, and RCA. 2016
+      href: https://lawfilesext.leg.wa.gov/law/wsr/2016/01/16-01-093.htm
+    - title: WAC 388-478-0020 Payment standards for TANF, SFA, and RCA. 2018
+      href: https://lawfilesext.leg.wa.gov/law/wsr/2018/09/18-09-088.htm
+    - title: WAC 388-478-0020 Payment standards for TANF, SFA, and RCA. 2021
+      href: https://lawfilesext.leg.wa.gov/law/wsr/2021/21/21-21-054.htm
+
+# Note: Values before Oct 25, 2020 are for households "with shelter costs".
+# WSR 20-20-007 eliminated the shelter cost distinction; all households now use these amounts.
 
 1:
+  2016-02-01: 332
+  2018-07-01: 363
+  2021-07-01: 417
   2024-01-01: 450
 2:
+  2016-02-01: 420
+  2018-07-01: 459
+  2021-07-01: 528
   2024-01-01: 570
 3:
+  2016-02-01: 521
+  2018-07-01: 569
+  2021-07-01: 654
   2024-01-01: 706
 4:
+  2016-02-01: 613
+  2018-07-01: 670
+  2021-07-01: 771
   2024-01-01: 833
 5:
+  2016-02-01: 706
+  2018-07-01: 772
+  2021-07-01: 888
   2024-01-01: 959
 6:
+  2016-02-01: 802
+  2018-07-01: 877
+  2021-07-01: 1_009
   2024-01-01: 1_090
 7:
+  2016-02-01: 927
+  2018-07-01: 1_013
+  2021-07-01: 1_165
   2024-01-01: 1_258
 8:
+  2016-02-01: 1_026
+  2018-07-01: 1_121
+  2021-07-01: 1_289
   2024-01-01: 1_392
 9:
+  2016-02-01: 1_126
+  2018-07-01: 1_231
+  2021-07-01: 1_416
   2024-01-01: 1_529
 10:
+  2016-02-01: 1_224
+  2018-07-01: 1_338
+  2021-07-01: 1_539
   2024-01-01: 1_662
diff --git a/policyengine_us/parameters/gov/states/wa/dshs/tanf/payment_standard/maximum_amount.yaml b/policyengine_us/parameters/gov/states/wa/dshs/tanf/payment_standard/maximum_amount.yaml
deleted file mode 100644
index 767f743858e..00000000000
--- a/policyengine_us/parameters/gov/states/wa/dshs/tanf/payment_standard/maximum_amount.yaml
+++ /dev/null
@@ -1,12 +0,0 @@
-description: Washington limits the grant payment to this amount under the Temporary Assistance for Needy Families program.
-
-values:
-  2024-01-01: 1_338
-
-metadata:
-  unit: currency-USD
-  period: month
-  label: Washington TANF maximum grant cap
-  reference:
-    - title: DSHS Eligibility A-Z Manual, Income - Effect of Income and Deductions on Eligibility
-      href: https://www.dshs.wa.gov/esa/income-table-contents/income-effect-income-and-deductions-eligibility-and-benefit-level
diff --git a/policyengine_us/parameters/gov/states/wa/dshs/tanf/resource_limit.yaml b/policyengine_us/parameters/gov/states/wa/dshs/tanf/resource_limit.yaml
index 797e2427d67..2ca947b374a 100644
--- a/policyengine_us/parameters/gov/states/wa/dshs/tanf/resource_limit.yaml
+++ b/policyengine_us/parameters/gov/states/wa/dshs/tanf/resource_limit.yaml
@@ -1,15 +1,24 @@
 description: Washington limits the Temporary Assistance for Needy Families program to households with countable resources up to this amount.
 
 values:
-  2022-01-01: 6_000
-  2024-01-01: 12_000
+  1998-09-01: 1_000
+  2019-02-01: 6_000
+  2024-02-01: 12_000
+
+# Note: Before Feb 1, 2019, Washington had a two-tier resource limit structure:                                                                                                 
+  # - Applicants: up to $1,000                                                                                                                                                    
+  # - Recipients: up to $1,000 plus an additional $3,000 in savings accounts                                                                                                      
+  # This file uses the applicant limit ($1,000) for the pre-2019 period.                                                                                                          
+  # E2SHB 1831 (2018) simplified this to a single $6,000 limit for all.
 
 metadata:
   unit: currency-USD
   period: year
   label: Washington TANF resource limit
   reference:
-    - title: Washington TANF State Plan 2022, page 13 - $6,000 cash resource limit
-      href: https://workfirst.wa.gov/sites/default/files/public/TANF_stateplan_2022_final.pdf#page=13
+    - title: WAC 388-470-0005 - Resource limits for cash assistance
+      href: https://app.leg.wa.gov/wac/default.aspx?cite=388-470-0005
+    - title: E2SHB 1831 (2018) - Resource limit increased to $6,000 effective Feb 1, 2019
+      href: https://app.leg.wa.gov/billsummary?BillNumber=1831&Year=2017
     - title: HB 1447 (2023 c 418) - Increased asset limit to $12,000 effective Feb 1, 2024
       href: https://app.leg.wa.gov/billsummary?BillNumber=1447&Year=2023
diff --git a/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/benefit/wa_tanf_payment_standard.yaml b/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/benefit/wa_tanf_payment_standard.yaml
index ba44a6e19d9..f75443e974b 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/benefit/wa_tanf_payment_standard.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/benefit/wa_tanf_payment_standard.yaml
@@ -46,3 +46,59 @@
     spm_unit_size: 3
   output:
     wa_tanf_payment_standard: 0
+
+# Historical tests - verify 2016 values apply in early 2018
+- name: Case 7, family size 1 in 2018-01.
+  period: 2018-01
+  input:
+    state_code: WA
+    spm_unit_size: 1
+  output:
+    # Uses 2016-02-01 value (before 2018-07-01 update)
+    wa_tanf_payment_standard: 332
+
+- name: Case 8, family size 3 in 2018-01.
+  period: 2018-01
+  input:
+    state_code: WA
+    spm_unit_size: 3
+  output:
+    # Uses 2016-02-01 value (before 2018-07-01 update)
+    wa_tanf_payment_standard: 521
+
+- name: Case 9, family size 10 in 2018-01.
+  period: 2018-01
+  input:
+    state_code: WA
+    spm_unit_size: 10
+  output:
+    # Uses 2016-02-01 value (before 2018-07-01 update)
+    wa_tanf_payment_standard: 1_224
+
+# Historical tests - verify 2021 values apply in 2022
+- name: Case 10, family size 1 in 2022-01.
+  period: 2022-01
+  input:
+    state_code: WA
+    spm_unit_size: 1
+  output:
+    # Uses 2021-07-01 value (15% increase)
+    wa_tanf_payment_standard: 417
+
+- name: Case 11, family size 3 in 2022-01.
+  period: 2022-01
+  input:
+    state_code: WA
+    spm_unit_size: 3
+  output:
+    # Uses 2021-07-01 value (15% increase)
+    wa_tanf_payment_standard: 654
+
+- name: Case 12, family size 10 in 2022-01.
+  period: 2022-01
+  input:
+    state_code: WA
+    spm_unit_size: 10
+  output:
+    # Uses 2021-07-01 value (15% increase)
+    wa_tanf_payment_standard: 1_539
diff --git a/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/eligibility/wa_tanf_income_eligible.yaml b/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/eligibility/wa_tanf_income_eligible.yaml
index c70145979a3..0c0bba89104 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/eligibility/wa_tanf_income_eligible.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/eligibility/wa_tanf_income_eligible.yaml
@@ -1,16 +1,17 @@
-- name: Zero gross earned income - eligible
-  period: 2024-01
+# Tests for Aug 2024+ income limits
+- name: Case 1, zero gross earned income.
+  period: 2025-01
   input:
     state_code: WA
     spm_unit_size: 3
     tanf_gross_earned_income: 0
   output:
-    # Income limit for family of 3: $1,912
+    # Income limit for family of 3: $1,912 (Aug 2024+)
     # Gross earned: $0 <= $1,912
     wa_tanf_income_eligible: true
 
-- name: Gross earned income below threshold - eligible
-  period: 2024-01
+- name: Case 2, gross earned income below threshold.
+  period: 2025-01
   input:
     state_code: WA
     spm_unit_size: 3
@@ -20,8 +21,8 @@
     # Gross earned: $1,500 <= $1,912
     wa_tanf_income_eligible: true
 
-- name: Gross earned income exactly at threshold - eligible
-  period: 2024-01
+- name: Case 3, gross earned income exactly at threshold.
+  period: 2025-01
   input:
     state_code: WA
     spm_unit_size: 3
@@ -31,8 +32,8 @@
     # Gross earned: $1,912 <= $1,912
     wa_tanf_income_eligible: true
 
-- name: Gross earned income one dollar over threshold - ineligible
-  period: 2024-01
+- name: Case 4, gross earned income one dollar over threshold.
+  period: 2025-01
   input:
     state_code: WA
     spm_unit_size: 3
@@ -42,8 +43,8 @@
     # Gross earned: $1,913 > $1,912
     wa_tanf_income_eligible: false
 
-- name: Gross earned income far over threshold - ineligible
-  period: 2024-01
+- name: Case 5, gross earned income far over threshold.
+  period: 2025-01
   input:
     state_code: WA
     spm_unit_size: 3
@@ -53,30 +54,30 @@
     # Gross earned: $3,000 > $1,912
     wa_tanf_income_eligible: false
 
-- name: Family size 1 - at threshold
-  period: 2024-01
+- name: Case 6, family size 1 at threshold.
+  period: 2025-01
   input:
     state_code: WA
     spm_unit_size: 1
     tanf_gross_earned_income: 1_400
   output:
-    # Income limit for family of 1: $1,400
+    # Income limit for family of 1: $1,400 (Aug 2024+)
     # Gross earned: $1,400 <= $1,400
     wa_tanf_income_eligible: true
 
-- name: Family size 10 - at maximum threshold
-  period: 2024-01
+- name: Case 7, family size 10 at maximum threshold.
+  period: 2025-01
   input:
     state_code: WA
     spm_unit_size: 10
     tanf_gross_earned_income: 3_824
   output:
-    # Income limit for family of 10: $3,824
+    # Income limit for family of 10: $3,824 (Aug 2024+)
     # Gross earned: $3,824 <= $3,824
     wa_tanf_income_eligible: true
 
-- name: Family size 15 - capped at size 10 limit
-  period: 2024-01
+- name: Case 8, family size 15 capped at size 10 limit.
+  period: 2025-01
   input:
     state_code: WA
     spm_unit_size: 15
@@ -86,11 +87,80 @@
     # Gross earned: $3,824 <= $3,824
     wa_tanf_income_eligible: true
 
-- name: Only calculate for WA
-  period: 2024-01
+- name: Case 9, only calculate for WA.
+  period: 2025-01
   input:
     state_code: MT
     spm_unit_size: 3
     tanf_gross_earned_income: 1_000
   output:
     wa_tanf_income_eligible: false
+
+# Historical tests - verify 2024-01 income limits (before Aug 2024 increase)
+- name: Case 10, 2024-01 uses Jan 2024 income limits.
+  period: 2024-01
+  input:
+    state_code: WA
+    spm_unit_size: 3
+    tanf_gross_earned_income: 1_412
+  output:
+    # Income limit for family of 3 in Jan 2024: $1,412
+    # Gross earned: $1,412 <= $1,412
+    wa_tanf_income_eligible: true
+
+- name: Case 11, 2024-01 over Jan 2024 limit.
+  period: 2024-01
+  input:
+    state_code: WA
+    spm_unit_size: 3
+    tanf_gross_earned_income: 1_413
+  output:
+    # Income limit for family of 3 in Jan 2024: $1,412
+    # Gross earned: $1,413 > $1,412
+    wa_tanf_income_eligible: false
+
+# Historical tests - verify 2018-01 income limits (2016 values)
+- name: Case 12, 2018-01 uses 2016 income limits.
+  period: 2018-01
+  input:
+    state_code: WA
+    spm_unit_size: 3
+    tanf_gross_earned_income: 1_042
+  output:
+    # Income limit for family of 3 in 2018-01: $1,042 (2016 value)
+    # Gross earned: $1,042 <= $1,042
+    wa_tanf_income_eligible: true
+
+- name: Case 13, 2018-01 over 2016 income limit.
+  period: 2018-01
+  input:
+    state_code: WA
+    spm_unit_size: 3
+    tanf_gross_earned_income: 1_043
+  output:
+    # Income limit for family of 3 in 2018-01: $1,042
+    # Gross earned: $1,043 > $1,042
+    wa_tanf_income_eligible: false
+
+# Historical tests - verify 2021-07 income limits (15% increase)
+- name: Case 14, 2022-01 uses July 2021 income limits.
+  period: 2022-01
+  input:
+    state_code: WA
+    spm_unit_size: 3
+    tanf_gross_earned_income: 1_308
+  output:
+    # Income limit for family of 3 in 2022-01: $1,308 (15% increase)
+    # Gross earned: $1,308 <= $1,308
+    wa_tanf_income_eligible: true
+
+- name: Case 15, 2022-01 over July 2021 limit.
+  period: 2022-01
+  input:
+    state_code: WA
+    spm_unit_size: 3
+    tanf_gross_earned_income: 1_309
+  output:
+    # Income limit for family of 3 in 2022-01: $1,308
+    # Gross earned: $1,309 > $1,308
+    wa_tanf_income_eligible: false
diff --git a/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/income/wa_tanf_countable_earned_income.yaml b/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/income/wa_tanf_countable_earned_income.yaml
index 7986cc66b3a..90d3b6525f4 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/income/wa_tanf_countable_earned_income.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/income/wa_tanf_countable_earned_income.yaml
@@ -1,5 +1,6 @@
-- name: Zero gross earned income - zero countable
-  period: 2024-01
+# Tests for Aug 2024+ rules (with $500 flat disregard)
+- name: Case 1, zero gross earned income.
+  period: 2025-01
   input:
     state_code: WA
     tanf_gross_earned_income: 0
@@ -7,8 +8,8 @@
     # Countable = max($0 - $500, 0) × 0.5 = $0
     wa_tanf_countable_earned_income: 0
 
-- name: Gross earned below disregard - zero countable
-  period: 2024-01
+- name: Case 2, gross earned below $500 disregard.
+  period: 2025-01
   input:
     state_code: WA
     tanf_gross_earned_income: 300
@@ -16,8 +17,8 @@
     # Countable = max($300 - $500, 0) × 0.5 = $0
     wa_tanf_countable_earned_income: 0
 
-- name: Gross earned exactly at disregard - zero countable
-  period: 2024-01
+- name: Case 3, gross earned exactly at $500 disregard.
+  period: 2025-01
   input:
     state_code: WA
     tanf_gross_earned_income: 500
@@ -25,46 +26,85 @@
     # Countable = max($500 - $500, 0) × 0.5 = $0
     wa_tanf_countable_earned_income: 0
 
-- name: Gross earned one dollar over disregard
-  period: 2024-01
+- name: Case 4, gross earned one dollar over disregard.
+  period: 2025-01
   input:
     state_code: WA
     tanf_gross_earned_income: 501
   output:
-    # Countable = ($501 - $500) × 0.5 = $0.50
+    # Countable = max($501 - $500, 0) × 0.5 = $0.50
     wa_tanf_countable_earned_income: 0.5
 
-- name: Gross earned moderately above disregard
-  period: 2024-01
+- name: Case 5, gross earned moderately above disregard.
+  period: 2025-01
   input:
     state_code: WA
     tanf_gross_earned_income: 1_000
   output:
-    # Countable = ($1,000 - $500) × 0.5 = $250
+    # Countable = max($1,000 - $500, 0) × 0.5 = $250
     wa_tanf_countable_earned_income: 250
 
-- name: Gross earned significantly above disregard
-  period: 2024-01
+- name: Case 6, gross earned significantly above disregard.
+  period: 2025-01
   input:
     state_code: WA
     tanf_gross_earned_income: 2_000
   output:
-    # Countable = ($2,000 - $500) × 0.5 = $750
+    # Countable = max($2,000 - $500, 0) × 0.5 = $750
     wa_tanf_countable_earned_income: 750
 
-- name: High gross earned income
-  period: 2024-01
+- name: Case 7, high gross earned income.
+  period: 2025-01
   input:
     state_code: WA
     tanf_gross_earned_income: 4_000
   output:
-    # Countable = ($4,000 - $500) × 0.5 = $1,750
+    # Countable = max($4,000 - $500, 0) × 0.5 = $1,750
     wa_tanf_countable_earned_income: 1_750
 
-- name: Only calculate for WA
-  period: 2024-01
+- name: Case 8, only calculate for WA.
+  period: 2025-01
   input:
     state_code: OR
     tanf_gross_earned_income: 1_000
   output:
     wa_tanf_countable_earned_income: 0
+
+# Historical tests - verify pre-Aug-2024 calculation (no $500 flat disregard)
+- name: Case 9, gross earned in 2018-01 with only 50% disregard.
+  period: 2018-01
+  input:
+    state_code: WA
+    tanf_gross_earned_income: 1_000
+  output:
+    # Pre-Aug 2024: No $500 flat disregard, only 50%
+    # Countable = $1,000 × 0.5 = $500
+    wa_tanf_countable_earned_income: 500
+
+- name: Case 10, low income in 2018-01.
+  period: 2018-01
+  input:
+    state_code: WA
+    tanf_gross_earned_income: 300
+  output:
+    # Countable = $300 × 0.5 = $150
+    wa_tanf_countable_earned_income: 150
+
+- name: Case 11, high income in 2018-01.
+  period: 2018-01
+  input:
+    state_code: WA
+    tanf_gross_earned_income: 2_000
+  output:
+    # Countable = $2,000 × 0.5 = $1,000
+    wa_tanf_countable_earned_income: 1_000
+
+- name: Case 12, 2024-01 uses only 50% disregard (before Aug 2024).
+  period: 2024-01
+  input:
+    state_code: WA
+    tanf_gross_earned_income: 1_000
+  output:
+    # 2024-01 is before Aug 2024, so no $500 flat disregard
+    # Countable = $1,000 × 0.5 = $500
+    wa_tanf_countable_earned_income: 500
diff --git a/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/integration.yaml b/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/integration.yaml
index 47315119d83..a1ae214e363 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/integration.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/integration.yaml
@@ -1,676 +1,749 @@
-- name: Single parent with 2 children - no income
-  period: 2024-01
+# Integration tests for WA TANF using Aug 2024+ rules
+# ($500 flat disregard + 50%, $12,000 resource limit, Aug 2024 income limits)
+
+- name: Case 1, single parent with 2 children, no income.
+  period: 2025-01
   input:
     people:
-      parent:
+      person1:
         age: 30
-      child1:
+      person2:
         age: 5
         is_tax_unit_dependent: true
-      child2:
+      person3:
         age: 3
         is_tax_unit_dependent: true
     families:
       family:
-        members: [parent, child1, child2]
+        members: [person1, person2, person3]
     spm_units:
       spm_unit:
-        members: [parent, child1, child2]
+        members: [person1, person2, person3]
     tax_units:
       tax_unit:
-        members: [parent, child1, child2]
+        members: [person1, person2, person3]
     households:
       household:
-        members: [parent, child1, child2]
+        members: [person1, person2, person3]
         state_code: WA
   output:
     wa_tanf_payment_standard: 706
     wa_tanf_countable_income: 0
     wa_tanf_eligible: true
     wa_tanf: 706
-- name: Single parent with 2 children - low earned income
-  period: 2024-01
+
+- name: Case 2, single parent with 2 children, low earned income.
+  period: 2025-01
   input:
     people:
-      parent:
+      person1:
         age: 30
-        employment_income_before_lsr: 12000
-      child1:
+        employment_income_before_lsr: 12_000
+      person2:
         age: 5
         is_tax_unit_dependent: true
-      child2:
+      person3:
         age: 3
         is_tax_unit_dependent: true
     families:
       family:
-        members: [parent, child1, child2]
+        members: [person1, person2, person3]
     spm_units:
       spm_unit:
-        members: [parent, child1, child2]
+        members: [person1, person2, person3]
     tax_units:
       tax_unit:
-        members: [parent, child1, child2]
+        members: [person1, person2, person3]
     households:
       household:
-        members: [parent, child1, child2]
+        members: [person1, person2, person3]
         state_code: WA
   output:
     wa_tanf_payment_standard: 706
+    # Monthly income: $12,000 / 12 = $1,000
+    # Countable earned = max($1,000 - $500, 0) × 0.5 = $250
     wa_tanf_countable_income: 250
     wa_tanf_eligible: true
     wa_tanf: 456
-- name: Single parent with 2 children - moderate earned income
-  period: 2024-01
+
+- name: Case 3, single parent with 2 children, moderate earned income.
+  period: 2025-01
   input:
     people:
-      parent:
+      person1:
         age: 30
-        employment_income_before_lsr: 21600
-      child1:
+        employment_income_before_lsr: 22_944
+      person2:
         age: 5
         is_tax_unit_dependent: true
-      child2:
+      person3:
         age: 3
         is_tax_unit_dependent: true
     families:
       family:
-        members: [parent, child1, child2]
+        members: [person1, person2, person3]
     spm_units:
       spm_unit:
-        members: [parent, child1, child2]
+        members: [person1, person2, person3]
     tax_units:
       tax_unit:
-        members: [parent, child1, child2]
+        members: [person1, person2, person3]
     households:
       household:
-        members: [parent, child1, child2]
+        members: [person1, person2, person3]
         state_code: WA
   output:
     wa_tanf_payment_standard: 706
-    wa_tanf_countable_income: 650
+    # Monthly income: $22,944 / 12 = $1,912 (at income limit)
+    # Countable earned = max($1,912 - $500, 0) × 0.5 = $706
+    wa_tanf_countable_income: 706
     wa_tanf_eligible: true
-    wa_tanf: 56
-- name: Single parent with 2 children - at income threshold
-  period: 2024-01
+    wa_tanf: 0
+
+- name: Case 4, two parents with 3 children, one parent working.
+  period: 2025-01
   input:
     people:
-      parent:
+      person1:
+        age: 32
+        employment_income_before_lsr: 18_000
+      person2:
         age: 30
-        employment_income_before_lsr: 22944
-      child1:
+      person3:
+        age: 8
+        is_tax_unit_dependent: true
+      person4:
         age: 5
         is_tax_unit_dependent: true
-      child2:
-        age: 3
+      person5:
+        age: 2
         is_tax_unit_dependent: true
     families:
       family:
-        members: [parent, child1, child2]
+        members: [person1, person2, person3, person4, person5]
     spm_units:
       spm_unit:
-        members: [parent, child1, child2]
+        members: [person1, person2, person3, person4, person5]
     tax_units:
       tax_unit:
-        members: [parent, child1, child2]
+        members: [person1, person2, person3, person4, person5]
     households:
       household:
-        members: [parent, child1, child2]
+        members: [person1, person2, person3, person4, person5]
         state_code: WA
   output:
-    wa_tanf_payment_standard: 706
-    wa_tanf_countable_income: 706
+    wa_tanf_payment_standard: 959
+    # Monthly income: $18,000 / 12 = $1,500
+    # Countable earned = max($1,500 - $500, 0) × 0.5 = $500
+    wa_tanf_countable_income: 500
     wa_tanf_eligible: true
-    wa_tanf: 0
-- name: Single parent with 2 children - over income threshold
-  period: 2024-01
+    wa_tanf: 459
+
+- name: Case 5, single parent with 1 child, unearned income only.
+  period: 2025-01
   input:
     people:
-      parent:
-        age: 30
-        employment_income_before_lsr: 23000
-      child1:
-        age: 5
-        is_tax_unit_dependent: true
-      child2:
-        age: 3
+      person1:
+        age: 45
+        social_security: 6_000
+      person2:
+        age: 10
         is_tax_unit_dependent: true
     families:
       family:
-        members: [parent, child1, child2]
+        members: [person1, person2]
     spm_units:
       spm_unit:
-        members: [parent, child1, child2]
+        members: [person1, person2]
     tax_units:
       tax_unit:
-        members: [parent, child1, child2]
+        members: [person1, person2]
     households:
       household:
-        members: [parent, child1, child2]
+        members: [person1, person2]
         state_code: WA
   output:
-    wa_tanf_eligible: false
-    wa_tanf: 0
-- name: Two parents with 3 children - one parent working
-  period: 2024-01
+    wa_tanf_payment_standard: 570
+    # Monthly unearned income: $6,000 / 12 = $500
+    # No earned income disregard for unearned income
+    wa_tanf_countable_income: 500
+    wa_tanf_eligible: true
+    wa_tanf: 70
+
+- name: Case 6, family size 1, pregnant woman.
+  period: 2025-01
   input:
     people:
-      parent1:
-        age: 32
-        employment_income_before_lsr: 24000
-      parent2:
-        age: 30
-      child1:
-        age: 8
-        is_tax_unit_dependent: true
-      child2:
-        age: 5
-        is_tax_unit_dependent: true
-      child3:
-        age: 2
-        is_tax_unit_dependent: true
+      person1:
+        age: 25
+        is_pregnant: true
     families:
       family:
-        members: [parent1, parent2, child1, child2, child3]
+        members: [person1]
     spm_units:
       spm_unit:
-        members: [parent1, parent2, child1, child2, child3]
+        members: [person1]
     tax_units:
       tax_unit:
-        members: [parent1, parent2, child1, child2, child3]
+        members: [person1]
     households:
       household:
-        members: [parent1, parent2, child1, child2, child3]
+        members: [person1]
         state_code: WA
   output:
-    wa_tanf_payment_standard: 959
-    wa_tanf_countable_income: 750
+    wa_tanf_payment_standard: 450
+    wa_tanf_countable_income: 0
     wa_tanf_eligible: true
-    wa_tanf: 209
-- name: Two parents with 2 children - both parents working
-  period: 2024-01
+    wa_tanf: 450
+
+- name: Case 7, family of 7, no income.
+  period: 2025-01
   input:
     people:
-      parent1:
-        age: 35
-        employment_income_before_lsr: 18000
-      parent2:
-        age: 33
-        employment_income_before_lsr: 9600
-      child1:
-        age: 7
+      person1:
+        age: 40
+      person2:
+        age: 38
+      person3:
+        age: 15
         is_tax_unit_dependent: true
-      child2:
-        age: 4
+      person4:
+        age: 13
+        is_tax_unit_dependent: true
+      person5:
+        age: 11
+        is_tax_unit_dependent: true
+      person6:
+        age: 9
+        is_tax_unit_dependent: true
+      person7:
+        age: 7
         is_tax_unit_dependent: true
     families:
       family:
-        members: [parent1, parent2, child1, child2]
+        members: [person1, person2, person3, person4, person5, person6, person7]
     spm_units:
       spm_unit:
-        members: [parent1, parent2, child1, child2]
+        members: [person1, person2, person3, person4, person5, person6, person7]
     tax_units:
       tax_unit:
-        members: [parent1, parent2, child1, child2]
+        members: [person1, person2, person3, person4, person5, person6, person7]
     households:
       household:
-        members: [parent1, parent2, child1, child2]
+        members: [person1, person2, person3, person4, person5, person6, person7]
         state_code: WA
   output:
-    wa_tanf_payment_standard: 833
-    wa_tanf_countable_income: 900
-    wa_tanf_eligible: false
-    wa_tanf: 0
-- name: Single parent with 1 child - unearned income only
-  period: 2024-01
+    wa_tanf_payment_standard: 1_258
+    wa_tanf_countable_income: 0
+    wa_tanf_eligible: true
+    wa_tanf: 1_258
+
+- name: Case 8, family size 10, no income.
+  period: 2025-01
   input:
     people:
-      parent:
+      person1:
         age: 45
-        social_security: 6000
-      child:
+      person2:
+        age: 43
+      person3:
+        age: 18
+      person4:
+        age: 16
+        is_tax_unit_dependent: true
+      person5:
+        age: 14
+        is_tax_unit_dependent: true
+      person6:
+        age: 12
+        is_tax_unit_dependent: true
+      person7:
         age: 10
         is_tax_unit_dependent: true
+      person8:
+        age: 8
+        is_tax_unit_dependent: true
+      person9:
+        age: 6
+        is_tax_unit_dependent: true
+      person10:
+        age: 4
+        is_tax_unit_dependent: true
     families:
       family:
-        members: [parent, child]
+        members: [person1, person2, person3, person4, person5, person6, person7,
+          person8, person9, person10]
     spm_units:
       spm_unit:
-        members: [parent, child]
+        members: [person1, person2, person3, person4, person5, person6, person7,
+          person8, person9, person10]
     tax_units:
       tax_unit:
-        members: [parent, child]
+        members: [person1, person2, person3, person4, person5, person6, person7,
+          person8, person9, person10]
     households:
       household:
-        members: [parent, child]
+        members: [person1, person2, person3, person4, person5, person6, person7,
+          person8, person9, person10]
         state_code: WA
   output:
-    wa_tanf_payment_standard: 570
-    wa_tanf_countable_income: 500
+    wa_tanf_payment_standard: 1_662
+    wa_tanf_countable_income: 0
     wa_tanf_eligible: true
-    wa_tanf: 70
-- name: Family of 4 - mixed earned and unearned income
-  period: 2024-01
+    wa_tanf: 1_662
+
+- name: Case 9, single parent with 1 child, earned income below $500.
+  period: 2025-01
   input:
     people:
-      parent:
-        age: 40
-        employment_income_before_lsr: 12000
-        social_security: 3600
-      child1:
-        age: 12
-        is_tax_unit_dependent: true
-      child2:
-        age: 9
-        is_tax_unit_dependent: true
-      child3:
-        age: 6
+      person1:
+        age: 28
+        employment_income_before_lsr: 4_800
+      person2:
+        age: 3
         is_tax_unit_dependent: true
     families:
       family:
-        members: [parent, child1, child2, child3]
+        members: [person1, person2]
     spm_units:
       spm_unit:
-        members: [parent, child1, child2, child3]
+        members: [person1, person2]
     tax_units:
       tax_unit:
-        members: [parent, child1, child2, child3]
+        members: [person1, person2]
     households:
       household:
-        members: [parent, child1, child2, child3]
+        members: [person1, person2]
         state_code: WA
   output:
-    wa_tanf_payment_standard: 833
-    wa_tanf_countable_income: 550
+    wa_tanf_payment_standard: 570
+    # Monthly income: $4,800 / 12 = $400
+    # Countable earned = max($400 - $500, 0) × 0.5 = $0
+    wa_tanf_countable_income: 0
     wa_tanf_eligible: true
-    wa_tanf: 283
-- name: Family size 1 - pregnant woman with no other children
-  period: 2024-01
+    wa_tanf: 570
+
+- name: Case 10, single parent with 3 children, earned income exactly at $500.
+  period: 2025-01
   input:
     people:
-      parent:
-        age: 25
-        is_pregnant: true
+      person1:
+        age: 32
+        employment_income_before_lsr: 6_000
+      person2:
+        age: 10
+        is_tax_unit_dependent: true
+      person3:
+        age: 7
+        is_tax_unit_dependent: true
+      person4:
+        age: 4
+        is_tax_unit_dependent: true
     families:
       family:
-        members: [parent]
+        members: [person1, person2, person3, person4]
     spm_units:
       spm_unit:
-        members: [parent]
+        members: [person1, person2, person3, person4]
     tax_units:
       tax_unit:
-        members: [parent]
+        members: [person1, person2, person3, person4]
     households:
       household:
-        members: [parent]
+        members: [person1, person2, person3, person4]
         state_code: WA
   output:
-    wa_tanf_payment_standard: 450
+    wa_tanf_payment_standard: 833
+    # Monthly income: $6,000 / 12 = $500
+    # Countable earned = max($500 - $500, 0) × 0.5 = $0
     wa_tanf_countable_income: 0
     wa_tanf_eligible: true
-    wa_tanf: 450
-- name: Family size 6 - moderate income
-  period: 2024-01
+    wa_tanf: 833
+
+- name: Case 11, family of 5, high unearned income.
+  period: 2025-01
   input:
     people:
-      parent1:
-        age: 38
-        employment_income_before_lsr: 18000
-      parent2:
-        age: 36
-      child1:
-        age: 14
+      person1:
+        age: 50
+        social_security: 12_000
+      person2:
+        age: 15
         is_tax_unit_dependent: true
-      child2:
-        age: 11
+      person3:
+        age: 13
         is_tax_unit_dependent: true
-      child3:
-        age: 8
+      person4:
+        age: 11
         is_tax_unit_dependent: true
-      child4:
-        age: 5
+      person5:
+        age: 9
         is_tax_unit_dependent: true
     families:
       family:
-        members: [parent1, parent2, child1, child2, child3, child4]
+        members: [person1, person2, person3, person4, person5]
     spm_units:
       spm_unit:
-        members: [parent1, parent2, child1, child2, child3, child4]
+        members: [person1, person2, person3, person4, person5]
     tax_units:
       tax_unit:
-        members: [parent1, parent2, child1, child2, child3, child4]
+        members: [person1, person2, person3, person4, person5]
     households:
       household:
-        members: [parent1, parent2, child1, child2, child3, child4]
+        members: [person1, person2, person3, person4, person5]
         state_code: WA
   output:
-    wa_tanf_payment_standard: 1090
-    wa_tanf_countable_income: 500
+    wa_tanf_payment_standard: 959
+    # Monthly unearned income: $12,000 / 12 = $1,000
+    wa_tanf_countable_income: 1_000
     wa_tanf_eligible: true
-    wa_tanf: 590
-- name: Family size 8 - testing maximum grant cap with no income
-  period: 2024-01
+    wa_tanf: 0
+
+- name: Case 12, single parent with 4 children, self-employment income.
+  period: 2025-01
   input:
     people:
-      parent1:
-        age: 42
-      parent2:
-        age: 40
-      child1:
-        age: 16
-        is_tax_unit_dependent: true
-      child2:
-        age: 14
-        is_tax_unit_dependent: true
-      child3:
+      person1:
+        age: 34
+        self_employment_income_before_lsr: 15_600
+      person2:
         age: 12
         is_tax_unit_dependent: true
-      child4:
+      person3:
         age: 10
         is_tax_unit_dependent: true
-      child5:
+      person4:
         age: 8
         is_tax_unit_dependent: true
-      child6:
+      person5:
         age: 6
         is_tax_unit_dependent: true
     families:
       family:
-        members: [parent1, parent2, child1, child2, child3, child4, child5, child6]
+        members: [person1, person2, person3, person4, person5]
     spm_units:
       spm_unit:
-        members: [parent1, parent2, child1, child2, child3, child4, child5, child6]
+        members: [person1, person2, person3, person4, person5]
     tax_units:
       tax_unit:
-        members: [parent1, parent2, child1, child2, child3, child4, child5, child6]
+        members: [person1, person2, person3, person4, person5]
     households:
       household:
-        members: [parent1, parent2, child1, child2, child3, child4, child5, child6]
+        members: [person1, person2, person3, person4, person5]
         state_code: WA
   output:
-    wa_tanf_payment_standard: 1392
-    wa_tanf_countable_income: 0
+    wa_tanf_payment_standard: 959
+    # Monthly income: $15,600 / 12 = $1,300
+    # Countable earned = max($1,300 - $500, 0) × 0.5 = $400
+    wa_tanf_countable_income: 400
     wa_tanf_eligible: true
-    wa_tanf: 1338
-- name: Family size 10 - testing maximum grant cap with low income
-  period: 2024-01
+    wa_tanf: 559
+
+# Historical integration tests for 2022-01 period
+# (50% disregard only, no $500 flat deduction, $6,000 resource limit)
+
+- name: Case 13, 2022-01 single parent with 2 children, no income.
+  period: 2022-01
   input:
     people:
-      parent1:
-        age: 45
-        employment_income_before_lsr: 9600
-      parent2:
-        age: 43
-      child1:
-        age: 18
-      child2:
-        age: 16
-        is_tax_unit_dependent: true
-      child3:
-        age: 14
-        is_tax_unit_dependent: true
-      child4:
-        age: 12
-        is_tax_unit_dependent: true
-      child5:
-        age: 10
+      person1:
+        age: 30
+      person2:
+        age: 5
         is_tax_unit_dependent: true
-      child6:
-        age: 8
+      person3:
+        age: 3
         is_tax_unit_dependent: true
-      child7:
-        age: 6
+    families:
+      family:
+        members: [person1, person2, person3]
+    spm_units:
+      spm_unit:
+        members: [person1, person2, person3]
+    tax_units:
+      tax_unit:
+        members: [person1, person2, person3]
+    households:
+      household:
+        members: [person1, person2, person3]
+        state_code: WA
+  output:
+    # 2021-07-01 payment standard for family of 3: $654 (15% increase, used in 2022-01)
+    wa_tanf_payment_standard: 654
+    wa_tanf_countable_income: 0
+    wa_tanf_eligible: true
+    wa_tanf: 654
+
+- name: Case 14, 2022-01 single parent with 2 children, low earned income.
+  period: 2022-01
+  input:
+    people:
+      person1:
+        age: 30
+        employment_income_before_lsr: 6_000
+      person2:
+        age: 5
         is_tax_unit_dependent: true
-      child8:
-        age: 4
+      person3:
+        age: 3
         is_tax_unit_dependent: true
     families:
       family:
-        members: [parent1, parent2, child1, child2, child3, child4, child5, child6,
-          child7, child8]
+        members: [person1, person2, person3]
     spm_units:
       spm_unit:
-        members: [parent1, parent2, child1, child2, child3, child4, child5, child6,
-          child7, child8]
+        members: [person1, person2, person3]
     tax_units:
       tax_unit:
-        members: [parent1, parent2, child1, child2, child3, child4, child5, child6,
-          child7, child8]
+        members: [person1, person2, person3]
     households:
       household:
-        members: [parent1, parent2, child1, child2, child3, child4, child5, child6,
-          child7, child8]
+        members: [person1, person2, person3]
         state_code: WA
   output:
-    wa_tanf_payment_standard: 1662
-    wa_tanf_countable_income: 150
+    wa_tanf_payment_standard: 654
+    # Monthly income: $6,000 / 12 = $500
+    # Countable earned = $500 × 0.5 = $250 (no $500 flat disregard in 2022)
+    wa_tanf_countable_income: 250
     wa_tanf_eligible: true
-    wa_tanf: 1338
-- name: Single parent with 1 child - earned income below $500 disregard
-  period: 2024-01
+    wa_tanf: 404
+
+- name: Case 15, 2022-01 single parent with 2 children, income at threshold.
+  period: 2022-01
   input:
     people:
-      parent:
-        age: 28
-        employment_income_before_lsr: 4800
-      child:
+      person1:
+        age: 30
+        employment_income_before_lsr: 15_696
+      person2:
+        age: 5
+        is_tax_unit_dependent: true
+      person3:
         age: 3
         is_tax_unit_dependent: true
     families:
       family:
-        members: [parent, child]
+        members: [person1, person2, person3]
     spm_units:
       spm_unit:
-        members: [parent, child]
+        members: [person1, person2, person3]
     tax_units:
       tax_unit:
-        members: [parent, child]
+        members: [person1, person2, person3]
     households:
       household:
-        members: [parent, child]
+        members: [person1, person2, person3]
         state_code: WA
   output:
-    wa_tanf_payment_standard: 570
-    wa_tanf_countable_income: 0
+    wa_tanf_payment_standard: 654
+    # Monthly income: $15,696 / 12 = $1,308 (at income limit)
+    # Countable earned = $1,308 × 0.5 = $654
+    wa_tanf_countable_income: 654
     wa_tanf_eligible: true
-    wa_tanf: 570
-- name: Single parent with 3 children - earned income exactly at $500
-  period: 2024-01
+    wa_tanf: 0
+
+# Historical integration tests for 2018-01 period
+# (50% disregard only, no $500 flat deduction, $1,000 resource limit)
+
+- name: Case 16, 2018-01 single parent with 2 children, no income.
+  period: 2018-01
   input:
     people:
-      parent:
-        age: 32
-        employment_income_before_lsr: 6000
-      child1:
-        age: 10
-        is_tax_unit_dependent: true
-      child2:
-        age: 7
+      person1:
+        age: 30
+      person2:
+        age: 5
         is_tax_unit_dependent: true
-      child3:
-        age: 4
+      person3:
+        age: 3
         is_tax_unit_dependent: true
     families:
       family:
-        members: [parent, child1, child2, child3]
+        members: [person1, person2, person3]
     spm_units:
       spm_unit:
-        members: [parent, child1, child2, child3]
+        members: [person1, person2, person3]
     tax_units:
       tax_unit:
-        members: [parent, child1, child2, child3]
+        members: [person1, person2, person3]
     households:
       household:
-        members: [parent, child1, child2, child3]
+        members: [person1, person2, person3]
         state_code: WA
   output:
-    wa_tanf_payment_standard: 833
+    # 2016-02-01 payment standard for family of 3: $521
+    wa_tanf_payment_standard: 521
     wa_tanf_countable_income: 0
     wa_tanf_eligible: true
-    wa_tanf: 833
-- name: Family of 5 - high unearned income exceeding payment standard
-  period: 2024-01
+    wa_tanf: 521
+
+- name: Case 17, 2018-01 single parent with 2 children, low earned income.
+  period: 2018-01
   input:
     people:
-      parent:
-        age: 50
-        social_security: 12000
-      child1:
-        age: 15
+      person1:
+        age: 30
+        employment_income_before_lsr: 6_000
+      person2:
+        age: 5
         is_tax_unit_dependent: true
-      child2:
-        age: 13
+      person3:
+        age: 3
         is_tax_unit_dependent: true
-      child3:
-        age: 11
+    families:
+      family:
+        members: [person1, person2, person3]
+    spm_units:
+      spm_unit:
+        members: [person1, person2, person3]
+    tax_units:
+      tax_unit:
+        members: [person1, person2, person3]
+    households:
+      household:
+        members: [person1, person2, person3]
+        state_code: WA
+  output:
+    wa_tanf_payment_standard: 521
+    # Monthly income: $6,000 / 12 = $500
+    # Countable earned = $500 × 0.5 = $250 (no $500 flat disregard in 2018)
+    wa_tanf_countable_income: 250
+    wa_tanf_eligible: true
+    wa_tanf: 271
+
+- name: Case 18, 2018-01 single parent with 2 children, income at threshold.
+  period: 2018-01
+  input:
+    people:
+      person1:
+        age: 30
+        employment_income_before_lsr: 12_504
+      person2:
+        age: 5
         is_tax_unit_dependent: true
-      child4:
-        age: 9
+      person3:
+        age: 3
         is_tax_unit_dependent: true
     families:
       family:
-        members: [parent, child1, child2, child3, child4]
+        members: [person1, person2, person3]
     spm_units:
       spm_unit:
-        members: [parent, child1, child2, child3, child4]
+        members: [person1, person2, person3]
     tax_units:
       tax_unit:
-        members: [parent, child1, child2, child3, child4]
+        members: [person1, person2, person3]
     households:
       household:
-        members: [parent, child1, child2, child3, child4]
+        members: [person1, person2, person3]
         state_code: WA
   output:
-    wa_tanf_payment_standard: 959
-    wa_tanf_countable_income: 1000
+    wa_tanf_payment_standard: 521
+    # Monthly income: $12,504 / 12 = $1,042 (at income limit)
+    # Countable earned = $1,042 × 0.5 = $521
+    wa_tanf_countable_income: 521
     wa_tanf_eligible: true
     wa_tanf: 0
-- name: Family of 7 - testing payment standard and cap boundary
+
+# Historical integration tests for 2024-01 period
+# (50% disregard only, no $500 flat deduction, $6,000 resource limit)
+
+- name: Case 19, 2024-01 single parent with 2 children, no income.
   period: 2024-01
   input:
     people:
-      parent1:
-        age: 40
-      parent2:
-        age: 38
-      child1:
-        age: 15
-        is_tax_unit_dependent: true
-      child2:
-        age: 13
-        is_tax_unit_dependent: true
-      child3:
-        age: 11
-        is_tax_unit_dependent: true
-      child4:
-        age: 9
+      person1:
+        age: 30
+      person2:
+        age: 5
         is_tax_unit_dependent: true
-      child5:
-        age: 7
+      person3:
+        age: 3
         is_tax_unit_dependent: true
     families:
       family:
-        members: [parent1, parent2, child1, child2, child3, child4, child5]
+        members: [person1, person2, person3]
     spm_units:
       spm_unit:
-        members: [parent1, parent2, child1, child2, child3, child4, child5]
+        members: [person1, person2, person3]
     tax_units:
       tax_unit:
-        members: [parent1, parent2, child1, child2, child3, child4, child5]
+        members: [person1, person2, person3]
     households:
       household:
-        members: [parent1, parent2, child1, child2, child3, child4, child5]
+        members: [person1, person2, person3]
         state_code: WA
   output:
-    wa_tanf_payment_standard: 1258
+    # 2024-01-01 payment standard for family of 3: $706
+    wa_tanf_payment_standard: 706
     wa_tanf_countable_income: 0
     wa_tanf_eligible: true
-    wa_tanf: 1258
-- name: Family of 9 - testing grant cap with moderate income
+    wa_tanf: 706
+
+- name: Case 20, 2024-01 single parent with 2 children, low earned income.
   period: 2024-01
   input:
     people:
-      parent1:
-        age: 44
-        employment_income_before_lsr: 12000
-      parent2:
-        age: 42
-      child1:
-        age: 17
-        is_tax_unit_dependent: true
-      child2:
-        age: 15
-        is_tax_unit_dependent: true
-      child3:
-        age: 13
-        is_tax_unit_dependent: true
-      child4:
-        age: 11
-        is_tax_unit_dependent: true
-      child5:
-        age: 9
-        is_tax_unit_dependent: true
-      child6:
-        age: 7
-        is_tax_unit_dependent: true
-      child7:
+      person1:
+        age: 30
+        employment_income_before_lsr: 6_000
+      person2:
         age: 5
         is_tax_unit_dependent: true
+      person3:
+        age: 3
+        is_tax_unit_dependent: true
     families:
       family:
-        members: [parent1, parent2, child1, child2, child3, child4, child5, child6,
-          child7]
+        members: [person1, person2, person3]
     spm_units:
       spm_unit:
-        members: [parent1, parent2, child1, child2, child3, child4, child5, child6,
-          child7]
+        members: [person1, person2, person3]
     tax_units:
       tax_unit:
-        members: [parent1, parent2, child1, child2, child3, child4, child5, child6,
-          child7]
+        members: [person1, person2, person3]
     households:
       household:
-        members: [parent1, parent2, child1, child2, child3, child4, child5, child6,
-          child7]
+        members: [person1, person2, person3]
         state_code: WA
   output:
-    wa_tanf_payment_standard: 1529
+    wa_tanf_payment_standard: 706
+    # Monthly income: $6,000 / 12 = $500
+    # Countable earned = $500 × 0.5 = $250 (no $500 flat disregard until Aug 2024)
     wa_tanf_countable_income: 250
     wa_tanf_eligible: true
-    wa_tanf: 1279
-- name: Single parent with 4 children - self-employment income
+    wa_tanf: 456
+
+- name: Case 21, 2024-01 single parent with 2 children, income at threshold.
   period: 2024-01
   input:
     people:
-      parent:
-        age: 34
-        self_employment_income_before_lsr: 15600
-      child1:
-        age: 12
-        is_tax_unit_dependent: true
-      child2:
-        age: 10
-        is_tax_unit_dependent: true
-      child3:
-        age: 8
+      person1:
+        age: 30
+        employment_income_before_lsr: 16_944
+      person2:
+        age: 5
         is_tax_unit_dependent: true
-      child4:
-        age: 6
+      person3:
+        age: 3
         is_tax_unit_dependent: true
     families:
       family:
-        members: [parent, child1, child2, child3, child4]
+        members: [person1, person2, person3]
     spm_units:
       spm_unit:
-        members: [parent, child1, child2, child3, child4]
+        members: [person1, person2, person3]
     tax_units:
       tax_unit:
-        members: [parent, child1, child2, child3, child4]
+        members: [person1, person2, person3]
     households:
       household:
-        members: [parent, child1, child2, child3, child4]
+        members: [person1, person2, person3]
         state_code: WA
   output:
-    wa_tanf_payment_standard: 959
-    wa_tanf_countable_income: 400
+    wa_tanf_payment_standard: 706
+    # Monthly income: $16,944 / 12 = $1,412 (at income limit)
+    # Countable earned = $1,412 × 0.5 = $706
+    wa_tanf_countable_income: 706
     wa_tanf_eligible: true
-    wa_tanf: 559
+    wa_tanf: 0
diff --git a/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/wa_tanf.yaml b/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/wa_tanf.yaml
index 182ce90f500..af802e387e0 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/wa_tanf.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/wa_tanf.yaml
@@ -52,7 +52,7 @@
   output:
     wa_tanf: 0
 
-- name: Large family - benefit capped by maximum grant cap
+- name: Large family - full payment standard
   period: 2024-01
   input:
     state_code: WA
@@ -60,12 +60,10 @@
     wa_tanf_payment_standard: 1_662
     wa_tanf_countable_income: 0
   output:
-    # Benefit before cap = $1,662 - $0 = $1,662
-    # Maximum grant cap = $1,338
-    # Benefit = min($1,662, $1,338) = $1,338
-    wa_tanf: 1_338
+    # Benefit = $1,662 - $0 = $1,662
+    wa_tanf: 1_662
 
-- name: Large family with income - benefit under cap
+- name: Large family with income - reduced benefit
   period: 2024-01
   input:
     state_code: WA
@@ -73,12 +71,10 @@
     wa_tanf_payment_standard: 1_529
     wa_tanf_countable_income: 250
   output:
-    # Benefit before cap = $1,529 - $250 = $1,279
-    # Maximum grant cap = $1,338
-    # Benefit = min($1,279, $1,338) = $1,279 (under cap)
+    # Benefit = $1,529 - $250 = $1,279
     wa_tanf: 1_279
 
-- name: Medium family - benefit exactly at cap
+- name: Medium family with partial income
   period: 2024-01
   input:
     state_code: WA
@@ -86,9 +82,7 @@
     wa_tanf_payment_standard: 1_392
     wa_tanf_countable_income: 54
   output:
-    # Benefit before cap = $1,392 - $54 = $1,338
-    # Maximum grant cap = $1,338
-    # Benefit = min($1,338, $1,338) = $1,338 (exactly at cap)
+    # Benefit = $1,392 - $54 = $1,338
     wa_tanf: 1_338
 
 - name: Only calculate for WA
@@ -100,3 +94,26 @@
     wa_tanf_countable_income: 0
   output:
     wa_tanf: 0
+
+# Historical tests - verify 2016 payment standards in early 2018
+- name: Case 10, eligible with no income in 2018-01.
+  period: 2018-01
+  input:
+    state_code: WA
+    wa_tanf_eligible: true
+    wa_tanf_payment_standard: 521
+    wa_tanf_countable_income: 0
+  output:
+    # Benefit = $521 - $0 = $521 (2016 value for size 3)
+    wa_tanf: 521
+
+- name: Case 11, eligible with partial income in 2018-01.
+  period: 2018-01
+  input:
+    state_code: WA
+    wa_tanf_eligible: true
+    wa_tanf_payment_standard: 521
+    wa_tanf_countable_income: 200
+  output:
+    # Benefit = $521 - $200 = $321
+    wa_tanf: 321
diff --git a/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/wa_tanf_resources_eligible.yaml b/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/wa_tanf_resources_eligible.yaml
index f5c722286d5..ea197c20540 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/wa_tanf_resources_eligible.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/wa/dshs/tanf/wa_tanf_resources_eligible.yaml
@@ -1,15 +1,52 @@
-- name: Households with assets at or below resource limit are eligible
-  period: 2024
+# Tests for Feb 2024+ resource limits ($12,000)
+- name: Case 1, assets at $12,000 resource limit.
+  period: 2025
   input:
     state_code: WA
     wa_tanf_countable_resources: 12_000
   output:
+    # Resource limit: $12,000 (Feb 2024+)
     wa_tanf_resources_eligible: true
 
-- name: Households with assets above resource limit are ineligible
-  period: 2024
+- name: Case 2, assets above $12,000 resource limit.
+  period: 2025
   input:
     state_code: WA
     wa_tanf_countable_resources: 13_000
   output:
     wa_tanf_resources_eligible: false
+
+# Historical tests - verify pre-Feb-2024 resource limits
+- name: Case 3, 2024-01 uses $6,000 limit (before Feb 2024).
+  period: 2024-01
+  input:
+    state_code: WA
+    wa_tanf_countable_resources: 6_000
+  output:
+    # Resource limit in Jan 2024: $6,000
+    wa_tanf_resources_eligible: true
+
+- name: Case 4, 2024-01 over $6,000 limit.
+  period: 2024-01
+  input:
+    state_code: WA
+    wa_tanf_countable_resources: 6_001
+  output:
+    wa_tanf_resources_eligible: false
+
+- name: Case 5, 2018-01 uses $1,000 limit (before 2019).
+  period: 2018-01
+  input:
+    state_code: WA
+    wa_tanf_countable_resources: 1_000
+  output:
+    # Resource limit in 2018: $1,000
+    wa_tanf_resources_eligible: true
+
+- name: Case 6, 2018-01 over $1,000 limit.
+  period: 2018-01
+  input:
+    state_code: WA
+    wa_tanf_countable_resources: 1_001
+  output:
+    wa_tanf_resources_eligible: false
diff --git a/policyengine_us/variables/gov/states/wa/dshs/tanf/eligibility/wa_tanf_eligible.py b/policyengine_us/variables/gov/states/wa/dshs/tanf/eligibility/wa_tanf_eligible.py
index 73bd5e436e0..ae1678dbce8 100644
--- a/policyengine_us/variables/gov/states/wa/dshs/tanf/eligibility/wa_tanf_eligible.py
+++ b/policyengine_us/variables/gov/states/wa/dshs/tanf/eligibility/wa_tanf_eligible.py
@@ -10,8 +10,6 @@ class wa_tanf_eligible(Variable):
     defined_for = StateCode.WA
 
     def formula(spm_unit, period, parameters):
-        person = spm_unit.members
-
         # Must meet demographic requirements (minor child with deprived parent
         # OR pregnant woman)
         # Per WAC 388-400-0005, eligibility follows federal TANF demographic rules
@@ -19,8 +17,8 @@ def formula(spm_unit, period, parameters):
 
         # Must have at least one U.S. citizen or qualified immigrant
         # Per WAC 388-424-0001, follows federal immigration eligibility
-        has_citizen = spm_unit.any(
-            person("is_citizen_or_legal_immigrant", period)
+        immigration_eligible = (
+            add(spm_unit, period, ["is_citizen_or_legal_immigrant"]) > 0
         )
 
         # Must meet income eligibility (gross earned income < limit)
@@ -36,7 +34,7 @@ def formula(spm_unit, period, parameters):
         # All requirements must be met
         return (
             demographic_eligible
-            & has_citizen
+            & immigration_eligible
             & income_eligible
             & resources_eligible
         )
diff --git a/policyengine_us/variables/gov/states/wa/dshs/tanf/income/wa_tanf_countable_earned_income.py b/policyengine_us/variables/gov/states/wa/dshs/tanf/income/wa_tanf_countable_earned_income.py
index eec600f3f46..8d8ac24bb36 100644
--- a/policyengine_us/variables/gov/states/wa/dshs/tanf/income/wa_tanf_countable_earned_income.py
+++ b/policyengine_us/variables/gov/states/wa/dshs/tanf/income/wa_tanf_countable_earned_income.py
@@ -14,20 +14,20 @@ def formula(spm_unit, period, parameters):
         # Get gross earned income from federal TANF variable
         gross_earned = add(spm_unit, period, ["tanf_gross_earned_income"])
 
-        # Apply earned income disregard per WAC 388-450-0170:
-        # "We start by deducting the first $500 of the total household's
-        # earned income. We then subtract 50% of the remaining monthly
-        # gross earned income."
+        # Apply earned income disregard per WAC 388-450-0170
         p = parameters(
             period
         ).gov.states.wa.dshs.tanf.income.deductions.earned_income_disregard
 
-        # Step 1: Deduct flat $500 family earnings disregard
-        remainder = max_(gross_earned - p.amount, 0)
+        # Step 1: Deduct flat family earnings disregard (if in effect)
+        # The $500 flat disregard was added by HB 1447, effective Aug 1, 2024.
+        # Before that date, only the 50% disregard applied.
+        flat_disregard = where(p.in_effect, p.amount, 0)
+        remainder = max_(gross_earned - flat_disregard, 0)
 
         # Step 2: Subtract (disregard) 50% of remaining income
         # Per WAC 388-450-0170(3): "subtract 50% of the remaining...income"
-        amount_disregarded = remainder * p.percentage_disregarded
+        amount_disregarded = remainder * p.rate
 
         # Countable earned income = remainder - amount disregarded
         return remainder - amount_disregarded
diff --git a/policyengine_us/variables/gov/states/wa/dshs/tanf/wa_tanf.py b/policyengine_us/variables/gov/states/wa/dshs/tanf/wa_tanf.py
index 1772bdcdeb0..6c90513c0f4 100644
--- a/policyengine_us/variables/gov/states/wa/dshs/tanf/wa_tanf.py
+++ b/policyengine_us/variables/gov/states/wa/dshs/tanf/wa_tanf.py
@@ -15,6 +15,7 @@ class wa_tanf(Variable):
 
     def formula(spm_unit, period, parameters):
         # Get payment standard based on assistance unit size
+        # (capped at maximum_family_size, typically 10)
         payment_standard = spm_unit("wa_tanf_payment_standard", period)
 
         # Get countable income (after all disregards and deductions)
@@ -24,11 +25,4 @@ def formula(spm_unit, period, parameters):
         # "The department calculates the amount of your cash assistance
         # by subtracting your AU's countable income from the applicable
         # payment standard."
-        grant_before_cap = max_(payment_standard - countable_income, 0)
-
-        # Apply maximum grant cap (unique to Washington)
-        # Per DSHS manual, grants cannot exceed $1,338
-        # regardless of family size (affects families of 8+)
-        p = parameters(period).gov.states.wa.dshs.tanf.payment_standard
-
-        return min_(grant_before_cap, p.maximum_amount)
+        return max_(payment_standard - countable_income, 0)