Illinois does not tax the federally taxed portion of Social Security benefits for state income-tax purposes. But Social Security income—including Medicare deductions—does count toward household income for Illinois’s senior property-tax assessment freeze. Those are separate rules for separate programs.
For tax year 2026, payable in 2027, the freeze’s household-income ceiling is $75,000. The program freezes eligible equalized assessed value (EAV), not the property-tax bill itself, and its income rules should not be confused with the state income-tax treatment of Social Security.
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Does Illinois tax Social Security?
For Illinois state income-tax purposes, the Illinois Department of Revenue says the state does not tax the federally taxed portion of Social Security benefits included in Illinois Form IL-1040, Line 1. That answers an income-tax question; it does not determine eligibility for a property-tax exemption. Illinois Department of Revenue: Social Security income.
Does Social Security count toward the Illinois senior freeze income limit?
Yes. The 2026 application for the Low-Income Senior Citizens Assessment Freeze Homestead Exemption, commonly called the senior freeze, lists Social Security income as part of household income and specifies that Medicare deductions are included. The application’s household-income calculation is not the same as federal taxable income or Illinois state taxable income. Review the current form instructions for the full calculation and any permitted adjustments. 2026 Form PTAX-340 and instructions.
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What is the income limit for the Illinois senior freeze?
The ceiling depends on the tax year. The Illinois Department of Revenue lists these household-income limits for the senior freeze:
| Tax year | Income limit | Property taxes payable |
|---|---|---|
| 2026 | $75,000 or less | 2027 |
| 2027 | $77,000 or less | 2028 |
| 2028 and after | $79,000 or less | 2029 and after |
These are program limits, not statements about whether a person’s Social Security benefits are taxable. For the 2026 application, the relevant household income is for 2025; the applicant must be 65 or older during 2026. Confirm the applicable year and current form before filing because thresholds and instructions can change. Illinois Department of Revenue: senior property-tax exemptions.
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Who can qualify and where do you apply?
The 2026 PTAX-340 sets out several requirements. In general, an applicant must:
- Be 65 or older during 2026.
- Have total household income of $75,000 or less for 2025.
- Have used the property as a principal residence on January 1, 2025 and January 1, 2026.
- Have owned the property or held a qualifying documented interest on both dates.
- Have been liable for the property taxes on both dates.
The form also provides for certain special circumstances, including some surviving spouses and residents of licensed health facilities, so these summary conditions are not a complete eligibility ruling.
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IDOR says applicants must file PTAX-340 each year with the chief county assessment office. In Cook County, file annually with the Cook County Assessor. Check the current form and your county office for local filing procedures and assistance. IDOR filing guidance.
Does a frozen assessment mean the tax bill cannot rise?
No. The exemption limits increases in eligible EAV by using a base-year value while the applicant remains qualified. It does not lock the tax bill. A local tax rate increase can raise the bill, and improvements to the property may affect its value. The exemption is calculated using the difference between current EAV and frozen base-year value, subject to the household-income limit. IDOR senior exemption overview.
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How the assessment freeze differs from senior tax deferral
These are separate forms of relief with different consequences. The freeze is an exemption that limits growth in taxable assessed value for eligible applicants. The Senior Citizens Real Estate Tax Deferral Program postpones payment of all or part of real estate taxes and special assessments. IDOR describes deferral as similar to a loan against the property’s market value: the state pays the tax, records a lien, and recovers the amount plus interest under the program’s rules when the property is sold or transferred.
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| Feature | Senior assessment freeze | Senior tax deferral |
|---|---|---|
| What it does | Limits increases in eligible taxable EAV while qualification continues. | Postpones payment of eligible property taxes or special assessments. |
| Repayment and lien | The program description identifies an exemption, not a tax-payment loan secured by a lien. | The state records a lien and recovers the deferred amount plus interest under program rules when the property is sold or transferred. |
| Income and filing | The 2026 PTAX-340 uses 2025 household income and requires annual filing with the applicable county assessment office. | Has separate annual eligibility and filing rules, including an application and recovery agreement filed with the county collector. |
Do not assume that qualifying for one program establishes eligibility for the other. The deferral has its own income limit and other requirements; check the current IDOR guidance and county collector before applying. IDOR: Senior Citizens Real Estate Tax Deferral Program.
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Do the rules change across state lines?
Yes, state income-tax treatment of Social Security can vary, and property-tax relief is a separate state and local question. Illinois’s answer about state income tax does not establish how another state treats Social Security or whether it offers a comparable property-tax program. A useful comparison must check each state’s current income-tax rules separately from its property-relief rules, including eligibility, income measurement, filing, and whether relief creates a repayment obligation or lien. The Connecticut General Assembly’s 2026 report compares state income-tax exemptions, but it does not establish another state’s senior property-tax eligibility rules. Connecticut General Assembly, 2026 report on state Social Security income-tax exemptions.
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