AOTC is effectively disabled in Enhanced CPS because eligibility input is never true

[MaxGhenis]

Summary

The Enhanced CPS artifact appears to make the American Opportunity Tax Credit effectively unavailable for all tax units, even though some people have nonzero qualified tuition expenses.

In PE-US, american_opportunity_credit depends on the person-level input is_eligible_for_american_opportunity_credit. That variable is a leaf/input variable, not a formula. In the current Enhanced CPS release, it appears to be false for every person, so american_opportunity_credit, refundable_american_opportunity_credit, and non_refundable_american_opportunity_credit are all zero for every tax unit.

Evidence

Using the bundled default dataset from policyengine.py / policyengine-us-data:

dataset: hf://policyengine/policyengine-us-data/enhanced_cps_2024.h5
periods checked: 2024 and 2025

refundable_payroll_tax_credit: nonzero=0/55,264 tax units
recovery_rebate_credit: nonzero=0/55,264 tax units
american_opportunity_credit: nonzero=0/55,264 tax units
refundable_american_opportunity_credit: nonzero=0/55,264 tax units
qualified_tuition_expenses: nonzero=662/101,384 people
is_full_time_college_student: true=3,748/101,384 people
is_eligible_for_american_opportunity_credit: true=0/101,384 people

Minimal check:

import numpy as np
from policyengine_us import Microsimulation

sim = Microsimulation()
for year in [sim.default_input_period, 2025]:
    print("period", year)
    for entity, var in [
        ("tax_unit", "american_opportunity_credit"),
        ("tax_unit", "refundable_american_opportunity_credit"),
        ("person", "qualified_tuition_expenses"),
        ("person", "is_full_time_college_student"),
        ("person", "is_eligible_for_american_opportunity_credit"),
    ]:
        arr = np.asarray(sim.calculate(var, year, map_to=entity, use_weights=False))
        if arr.dtype == bool:
            print(entity, var, int(arr.sum()), "/", arr.size)
        else:
            print(entity, var, int(np.count_nonzero(np.nan_to_num(arr))), "/", arr.size, float(np.nansum(arr)))

Why this matters

AOTC eligibility requires more than tuition expenses, but setting is_eligible_for_american_opportunity_credit false for all people means Enhanced CPS cannot represent any AOTC claims. This also makes income_tax_refundable_credits omit refundable AOTC mechanically, regardless of tuition expenses or student status.

Possible fixes

• Populate/impute is_eligible_for_american_opportunity_credit in Enhanced CPS.
• Add or impute the underlying eligibility inputs needed to derive it: credential program, at least half-time enrollment, first-four-years status, prior AOTC/Hope claim years, felony drug conviction exclusion, and eligible-institution/1098-T assumptions.
• If AOTC is intentionally unsupported in public Enhanced CPS, document this limitation and consider suppressing or zeroing related tuition inputs that could otherwise imply AOTC support.

Related but not duplicate: PolicyEngine/policyengine-us#4034 discusses consolidating tuition variables. This issue is about the Enhanced CPS data path making AOTC eligibility false for every person.