[PavelMakarchuk]

Stacked on #10280 (branch ctc-qualifying-children-filer-id), which is not merged yet. This PR's base is that branch; retarget it to main after #10280 merges.

Summary

The Maine sales tax fairness credit and the property tax fairness credit count each "qualifying child or dependent" for whom the filer "can claim the federal child tax credit pursuant to the Code, Section 24" (36 MRSA 5213-A(1)(A-1)(2) and 5219-KK(1)(A-1)(2)-(3)). Section 24 includes the credit for other dependents (ODC, IRC 24(h)(4)). me_fairness_credit_qualifying_children (added in #10280) counted only CTC-qualifying children. It did not count dependents for whom only the ODC is allowed, for example a 17-year-old, a child with an ITIN but no SSN, or an adult dependent.

The variable now counts each dependent with a section 24 amount before the phase-out (ctc_individual_maximum > 0, the sum of ctc_child_individual_maximum and ctc_adult_individual_maximum). So the count follows the federal TIN tests for both credits. The ODC amount is $0 before 2018, so earlier years count only CTC children.

Sources

• 2025 Form 1040ME instructions, PDF page 5, line 13a: "Enter the number of qualifying children and dependents for whom you are eligible to claim the federal child tax credit or the credit for other dependents". PDF page 11: both fairness credits use "the number of qualifying children and dependents on Form 1040ME, line 13a".
• 2025 Schedule PTFC/STFC, PDF pages 2-4: the line 8 benefit base table, the income limit table and the line 17 credit table all use Form 1040ME line 13a.
• 2025 Schedule 8812 instructions: the ODC TIN rules.

Changes

• me_fairness_credit_qualifying_children: counts dependents with ctc_individual_maximum > 0. Label, documentation and references updated.
• me_sales_tax_fairness_credit and me_property_tax_fairness_credit_benefit_base read this count, so both change for filers with ODC-only dependents. No other variable reads it.

Tests

YAML only, in me_fairness_credit_qualifying_children.yaml. No Python tests, so no change in CI cost. The expected credit amounts come from the 2025 Schedule PTFC/STFC tables (line 8, and line 17 at total income $10,000).

Case (2025 unless stated)	Count	PTFC benefit base	STFC
Joint, one dependent age 17 with an SSN	1	$4,050	$250
Joint, child age 8 with an ITIN but no SSN	1		$250
Head of household, adult dependent age 20 and child age 10	2	$4,050	$250
Joint, dependent age 17 with no TIN	0	$3,300	$215
Joint, child age 8, dependent age 17, dependent age 19 with no TIN	2		$280
2017, joint, child age 8 and dependent age 17	1

The three cases from #10280 still pass without changes.

Local runs (macOS):

Suite	Result
baseline/gov/states/me (test_batched.py --mode per-subdir --workers 1)	652 passed (646 before, plus 6 new)
contrib/states/me and other YAML files with Maine households (8 files)	113 passed
tests/core/test_dependent_elsewhere_head_spouse_swap_invariance.py, test_claimable_filer_or_me_hi_invariants.py	12 passed

No partner test file has a Maine household.

Axiom parity

axiom: TheAxiomFoundation/rulespec-us#1686 queued

rulespec-us has no us-me/statutes/36/5219-KK module, and us-me/statutes/36/5213-A.yaml encodes only refundability (eligibility and amounts are deferred; complete Maine corpus extraction is in TheAxiomFoundation/rulespec-us#1651). TheAxiomFoundation/rulespec-us#1686 queues the 5219-KK benefit-base selector on "lawful section 24 dependents" and is blocked on the Maine corpus re-pin. Its companion cases used only a child age 8, so it had no ODC-only case. This comment adds four companions from this PR's YAML, with caps from the 2025 Schedule PTFC/STFC line 8 table (for example, joint with one dependent age 17: line 13a is 1, $4,050 cap; the same dependent with no TIN: $3,300). The STFC amounts belong to §5213-A, which is outside that issue (TheAxiomFoundation/rulespec-us#1619 and TheAxiomFoundation/rulespec-us#1651).

Not in scope

me_dependent_exemption_credit_amount_person (36 MRSA 5219-SS uses the same line 13a count) counts every is_tax_unit_dependent, without the TIN tests. That is a separate gap.

🤖 Generated with Claude Code

[hua7450]

Approving this PR's own change. It is the Maine follow-up I raised on 10280, and it lands after 10280, which still has changes requested.

I checked it against 36 MRSA 5213-A(1)(A-1) and 5219-KK(1)(A-1), Form 1040ME line 13a (2025 instructions: "qualifying children and dependents for whom you are eligible to claim the federal child tax credit or the credit for other dependents") and the 2025 Schedule PTFC/STFC tables. I also recomputed all nine cases in me_fairness_credit_qualifying_children.yaml by hand.

Under baseline law, ctc_individual_maximum > 0 matches the line 13a count in every year from 2018 to 2026. It covers:

• CTC children;
• 17-year-olds and adult dependents with a TIN;
• children with an ITIN only;
• children of a filer without a valid SSN, through 24(h)(4)(C).

It excludes dependents without a TIN, returns where a filer has no TIN, and filers claimable as dependents (152(b)(1)). No other test reads this count.

Nits:

1. Name. The variable now counts "qualifying children and dependents", but it is still named me_fairness_credit_qualifying_children, and me_sales_tax_fairness_credit still calls the value children. The variable is new in unmerged 10280, so a rename such as me_fairness_credit_dependents is cheap now and becomes an API name once merged.
2. TIN comment. "The dependent and the filer still need a TIN (IRC 24(e))" holds for the filer (24(e)(2)) and for qualifying children (24(e)(1)). The TIN rule for an older dependent comes from the Schedule 8812 instructions ("Dependent required to have a TIN"), not 24(e).
3. 2017 case. The name "Maine counts only Child Tax Credit children before the credit for other dependents in 2017" reads as Maine law. Before 2018, both statutes keyed on personal exemptions, not on a section 24 count. Please describe it as the model's behaviour (the federal ODC amount is $0 before 2018), or drop the case, and reword the matching sentence in the formula comment.
4. Reference. The i1040s8.pdf href is the rolling current-year file, labelled as the 2025 instructions. Use https://www.irs.gov/pub/irs-prior/i1040s8--2025.pdf#page=1 (the same line comes from 10280).
5. Changelog. The filer claims the credit for other dependents; the dependent does not "get" it. Suggested: "Count dependents for whom the filer can claim the federal credit for other dependents, not only Child Tax Credit children, in the Maine sales tax and property tax fairness credits."
6. Optional case. The new cases have no rent or property tax, so the final property tax fairness credit is $0 either way. A 2025 joint case would show the dollar effect: $70,000 income, $5,000 property tax and one 17-year-old dependent give a $4,050 benefit base and a $1,000 credit, against $3,300 and $500 at the base branch.

Note on reforms: because the count tests a federal amount rather than eligibility, afa_other_dependent_credit changes Maine's count. That reform sets ctc.amount.adult_dependent to 0 from 2025 and moves the credit for other dependents into its own other_dependent_credit. Under AFA, Maine therefore stops counting adult dependents and ITIN-only children, although AFA still gives them a federal credit. Baseline results are exact. A short note is enough here. A person-level eligibility flag could replace the amount test later and serve 10286 too (see my comment there).

Follow-ups, separate PRs:

• The fairness credit parameters start in 2021, so 2018-2020 use 2021 values.
• The 2018-2020 under-65 property tax cap is $740, but 5219-KK sets $750.
• Nine fairness parameter files have a reference titled 2024 that links the 2023 schedule.