Use current-year federal EITC for Indiana EITC childless filers

[MaxGhenis]

Summary

Follow-up to #8875 / #8831. PR #8875 routed Indiana with-children filers to the current-year federal EITC but kept childless filers on a frozen Jan 1, 2023 IRC snapshot, based on a rationale the primary sources contradict. This PR removes the where(child_count > 0, current, frozen) split so all Indiana filers use the current-year federal EITC.

Why the split was wrong

• 2025 Schedule IN-EIC (State Form 49469, R25/9-25) Section A applies to every filer: Line A-1 is "the earned income credit from your federal income tax return," multiplied by 10%. Section B is a qualifying-child information schedule (names, SSNs, ages), not a computation path — it does not carve out childless filers. Use current-year federal EITC for Indiana EITC with-children filers #8875 had the Section A / Section B roles reversed.
• DOR Information Bulletin Add SchXYZTax #92 describes the IRC §32 January 1, 2023 conformity freeze (IC 6-3-1-11) uniformly for "the Indiana EITC," with no childless-specific language.
• The ARPA childless EITC expansion expired January 1, 2022, so for TY2023 onward the freeze's only operative effect is that Indiana does not automatically adopt post-snapshot federal EITC changes — and for this window those changes are inflation indexing only, the same indexing Use current-year federal EITC for Indiana EITC with-children filers #8875 accepted for with-children filers.

Before / after (childless filer, age 30, $8,000 wages)

Tax year	in_eitc before	in_eitc after	Basis
2025	$60.00 (10% × frozen 2023 max $600)	$61.20	10% × current federal $612
2026	$61.20	$61.20 (unchanged)	frozen 2026 snapshot already equals current

Note on the expected value. The originating issue suggested the 2025 childless value would become $64.90 (10% × the indexed $649 max). Recomputing from the model gives $61.20: at $8,000 earnings the 2025 federal childless EITC is phase-in-limited to $612 (7.65% × $8,000), which is below the $649 maximum, so the max does not bind at this test household's income. $64.90 would only apply to a childless filer already at or above the max (earnings ≳ $8,484). The test uses the model-computed $61.20, which equals the value the existing (already-passing) 2026 childless test produces for the identical household — a consistency check, since the federal EITC computation is the same in both years for this case.

With-children cases are unchanged ($432.80 → $433 for TY2025; $442.70 for TY2026), as #8875 already routed them to the current-year federal EITC. Their test comments are corrected to cite Section A (all filers) rather than Section B.

Dead-code check

The frozen-snapshot code path is not dead after this change:

• in_eitc_eligible.py still computes its own frozen-snapshot frozen_federal_eitc for the Indiana EITC eligibility test (frozen_federal_eitc > 0) — a separate, uniform (no child-count split) computation that this PR leaves untouched.
• The shared helpers calculate_eitc_demographic_eligibility and calculate_eitc_like_amount remain in active use by CO, DC, IL, and WA credits.
• The static_conformity_in_effect gate itself is retained in in_eitc.py — it still distinguishes the 2023+ static-conformity regime from the pre-2011 (not decoupled) and 2011–2022 (fully-decoupled parameter) branches. Only the frozen amount recomputation inside the branch was removed; the unused state_eitc_helpers import was dropped accordingly.

Tests

• Updated in_eitc.yaml: childless 2025 → $61.20 (was $60); comments corrected to Section A across all four TY2025/TY2026 cases.
• changelog.d/in-eitc-childless-current.fixed.md added.
• Full Indiana directory: 438 passed (policyengine_us/tests/policy/baseline/gov/states/in/), including in_eitc.yaml (7) and in_eitc_eligible.yaml (8).
• Regression check on states sharing state_eitc_helpers.py — CO / DC / IL / WA: 81 passed.
• ruff format --check and ruff check clean on the edited variable; package smoke-imports.

References: 2025 Schedule IN-EIC (State Form 49469); DOR Information Bulletin #92; IC 6-3-1-11; IC 6-3.1-21; Indiana SEA 243 (2025).

Fixes #8898

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.50%. Comparing base (f9e58e7) to head (28fa773).
⚠️ Report is 69 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##              main    #8902      +/-   ##
===========================================
- Coverage   100.00%   97.50%   -2.50%     
===========================================
  Files            3        1       -2     
  Lines           55       40      -15     
  Branches         0        3       +3     
===========================================
- Hits            55       39      -16     
- Partials         0        1       +1     

Flag	Coverage Δ
unittests	97.50% <100.00%> (-2.50%)	⬇️

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[MaxGhenis]

Merged over the codecov/project gate: patch coverage passed (100% of modified lines), the full test suite is green after one infra-killed shard rerun, and codecov/project is the recurring stale-base comparison flake (same diagnosis as #8875).