Backdating Washington TANF

[hua7450]

Summary

Fixes #7199

Adds historical parameter values to Washington TANF, extending data back to 2016 based on Washington State Register (WSR) filings.

Changes

Parameters Updated

Parameter	Historical Values Added
payment_standard/amount.yaml	2016-02-01, 2018-07-01, 2021-07-01
income/limit.yaml	2016-02-01, 2018-07-01, 2021-07-01, split 2024 into 2024-01-01 and 2024-08-01
resource_limit.yaml	1998-09-01 ($1,000), fixed dates: 2019-02-01 ($6,000), 2024-02-01 ($12,000)
maximum_family_size.yaml	2016-01-01
earned_income_disregard/rate.yaml	1998-09-01 (renamed from percentage_disregarded.yaml)
earned_income_disregard/amount.yaml	Fixed date to 2024-08-01
earned_income_disregard/in_effect.yaml	New file - boolean to track when $500 flat disregard applies

Parameters Deleted

• payment_standard/maximum_amount.yaml - Redundant with maximum_family_size capping payment standard at size 10

Variables Updated

• wa_tanf.py - Removed maximum_amount cap (handled by maximum_family_size)
• wa_tanf_countable_earned_income.py - Updated to use in_effect and rate parameters

Tests Updated

• Added historical tests for 2018-01 period verifying 2016 parameter values
• Added historical tests for 2022-01 period verifying 2021-07-01 parameter values (15% increase)
• Fixed tests to use correct periods (2025-01 for Aug 2024+ rules, 2024-01 for pre-Aug rules)
• Removed references to deleted maximum grant cap

Regulatory Sources

• WAC 388-478-0020 - Payment standards
• WAC 388-478-0035 - Income limits
• WAC 388-470-0005 - Resource limits
• WAC 388-450-0170 - Earned income deductions
• WSR 16-01-093 - 2016 values
• WSR 18-09-088 - 2018 values
• WSR 21-21-054 - 2021 values (15% increase effective July 1, 2021)
• WSR 23-23-054 - 2024 values
• E2SHB 1831 - Resource limit increase to $6,000 (2019)
• HB 1447 - $500 flat disregard and $12,000 resource limit (2024)

Test Plan

• All 83 WA TANF tests pass
• Historical tests verify 2018-01 uses 2016 parameter values
• Historical tests verify 2022-01 uses 2021-07-01 parameter values (15% increase)
• Tests verify correct behavior before and after Aug 2024 policy changes

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (60c5dcc) to head (2763d1a).
⚠️ Report is 25 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##             main     #7202       +/-   ##
============================================
+ Coverage   73.76%   100.00%   +26.23%     
============================================
  Files        3666         3     -3663     
  Lines       52712        43    -52669     
  Branches      263         0      -263     
============================================
- Hits        38882        43    -38839     
+ Misses      13815         0    -13815     
+ Partials       15         0       -15     

Flag	Coverage Δ
unittests	100.00% <100.00%> (+26.23%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.