Backdate Nebraska ADC parameters

[hua7450]

Closes #7465
Closes #7090

Summary

Backdate Nebraska ADC (Aid to Dependent Children) parameters to cover 2015–2025, adding biennial CPI-adjusted Standard of Need values and scalar parameters for all historical periods.

Regulatory Authority

Document	URL	Coverage
Neb. Rev. Stat. 43-512(3)	Link	Payment standard = 55% of SON
Neb. Rev. Stat. 43-513(1)	Link	Standard of Need biennial CPI adjustment
Neb. Rev. Stat. 68-1726	Link	Earned income disregards, resource limits
DHHS 468-000-209 (2021)	PDF	2021 SON & Payment Max tables
Title 468 NAC Chapter 3 (2025)	PDF	2025 SON & Payment Max tables
ACF-202 TANF Caseload Reduction Report	PDF	SON(3) for all years 2007–2025
NE Legislature 2024 TANF Report	PDF	2023 SON & increment
Urban Institute WRDTP Policy Tables	Link	2015, 2017, 2019 SON values
NE Secretary of State Proposal 1632	PDF	Complete 2015 SON table

Standard of Need by Unit Size

Size	2015-07-01	2017-07-01	2019-07-01	2021-07-01	2023-07-01	2025-07-01
1	$541	$556	$579	$601	$683	$727
2	$667	$686	$714	$741	$843	$897
3	$793	$816	$849	$881	$1,003	$1,067
4	$919	$946	$984	$1,021	$1,163	$1,237
5	$1,045	$1,076	$1,119	$1,161	$1,323	$1,407
6	$1,171	$1,206	$1,254	$1,301	$1,483	$1,577
7	$1,297	$1,336	$1,389	$1,441	$1,643	$1,747
8	$1,423	$1,466	$1,524	$1,581	$1,803	$1,917
9	$1,549	$1,596	$1,659	$1,721	$1,963	$2,087
10	$1,675	$1,726	$1,794	$1,861	$2,123	$2,257
Addl	+$126	+$130	+$135	+$140	+$160	+$170

Scalar Parameters

Parameter	Value	Effective Date	Source
Payment standard rate	55%	2015-09-01	Neb. Rev. Stat. 43-512(3), LB 607
Earned income disregard (initial)	20%	2015-09-01	Neb. Rev. Stat. 68-1726(3)(a)(i)
Earned income disregard (ongoing)	50%	2015-09-01	Neb. Rev. Stat. 68-1726(3)(a)(ii)
Resource limit (1 person)	$4,000	2015-07-01	Neb. Rev. Stat. 68-1726(1)
Resource limit (2+ persons)	$6,000	2015-07-01	Neb. Rev. Stat. 68-1726(1)
Max unit size	10	2015-07-01	Title 468 NAC Chapter 3

Benefit Calculation (Gap Budgeting)

1. Countable Earned Income = Gross Earned × (1 − disregard rate)
   • Initial applicants: 20% disregard → 80% countable
   • Ongoing recipients: 50% disregard → 50% countable
2. Gap = max(Standard of Need − Countable Earned Income, 0)
3. Maximum Benefit = min(Gap, Payment Standard)
4. Final Benefit = max(Maximum Benefit − Unearned Income, 0)

Source: Title 468 NAC Chapter 3

Changes in This PR

• Backdated Standard of Need and additional person increment for 2015, 2017, 2019, and 2023
• Fixed 2017 increment from $131 → $130 and 2019 increment from $136 → $135, per ACF-202 form (page 3)
• Set payment standard rate effective date to 2015-09-01 (LB 607)
• Set earned income disregard effective dates to 2015-09-01
• Set resource limits and max unit size effective dates to 2015-07-01
• Added historical-period test coverage (2016, 2018, 2020, 2022, 2026)
• Updated all test expectations to match corrected parameter values

Pre-existing Issue (Not Addressed)

The 2025 official Payment Maximum table (Title 468 p.9) diverges slightly from SON × 55%. For example, size 3: $1,067 × 0.55 = $586.85, but official table shows $584. For 2021 and earlier the formula matches. This may warrant a separate parameter table for payment maximums in a future PR.

Co-Authored-By: Claude Opus 4.6 noreply@anthropic.com

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.76%. Comparing base (55a0045) to head (3072798).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #7470       +/-   ##
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- Coverage   97.82%   72.76%   -25.07%     
===========================================
  Files           3     3900     +3897     
  Lines          92    56278    +56186     
  Branches        2      271      +269     
===========================================
+ Hits           90    40949    +40859     
- Misses          1    15307    +15306     
- Partials        1       22       +21     

Flag	Coverage Δ
unittests	72.76% <ø> (-25.07%)	⬇️

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