Missing Illinois 2022 property tax rebate (Family Relief Plan)

[DTrim99]

Issue

PolicyEngine models the 2022 Illinois income tax rebate (il_income_tax_rebate, $50/filer + $100/dependent) but not the companion property tax rebate from the same 2022 Illinois Family Relief Plan (PA 102-0700).

Per the Illinois announcement:

The State of Illinois is also providing property tax rebates for eligible homeowners in an amount equal to the property tax credit they qualified for on their 2021 returns, up to a maximum of $300. The rebate is not allowed if a taxpayer's adjusted gross income for the taxable year exceeds $500,000 for returns with a federal filing status of married filing jointly, or $250,000 for all other returns.

So the property tax rebate is:

• equal to the 2021 Illinois property tax credit (Schedule ICR, 5% of property tax), capped at $300
• disallowed if AGI > $500,000 (MFJ) / $250,000 (other) — a higher limit than the income-tax rebate's $400k/$200k

Impact (TAXSIM #1172)

IL 2021 joint, property tax $1,432 → property tax credit $71.60. PE reports the $100 income-tax rebate but omits the $71.60 property-tax rebate, so the total 2022 rebate is understated ($100 vs $171.60).

Fix

Add an il_property_tax_rebate variable (= min($300, 2021 IL property tax credit), gated on the $500k/$250k AGI limit), modeled as a 2021 refundable credit like il_income_tax_rebate.

Reported via PolicyEngine/policyengine-taxsim#1172.