Open your tax year 2025 second-installment bill. The amount due has a firm date: **Thursday, October 1, 2026**, according to the Cook County Treasurer. The Treasurer’s office said **1.8 million bills** would be mailed on or before September 1, 2026. The Treasurer lists the tax year 2025 first installment as due Wednesday, April 1, 2026. The tax year 2024 second installment was due Monday, December 15, 2025. Do not use last year’s schedule as a proxy. Before you close the page or put the paper aside, stay with it for another minute. This is the installment where your property-tax exemptions appear, and those lines can tell you whether the bill reflects the relief you expected.
Quick Answer
The tax year 2025 second installment is due Thursday, October 1, 2026. Exemptions show up on this bill. A missing Homeowner Exemption, Senior Homestead, or Senior Freeze line is a Certificate of Error with the Assessor, not a Board complaint labeled Property Over-Assessed. Pay the bill on time either way.
Start with the exemption entries themselves. Look for **Homeowner Exemption**, **Senior Citizens Homestead Exemption**, and **Senior Freeze** if each applies to you. Similar names do not mean interchangeable benefits. Each one changes equalized assessed value, or EAV, in a different way. An absent line tells you which benefit is not reflected on the bill. It does not, by itself, tell you why.
The **Homeowner Exemption** is Cook County’s name for the general homestead relief available to an eligible owner-occupant. It reduces EAV by up to **$10,000**. That is not $10,000 taken off the check you write. The statutory amount is the increase over the property’s 1977 EAV, up to that $10,000 cap, not an automatic $10,000 off every parcel. The actual tax effect depends on the qualifying EAV reduction and the local tax rate. The Assessor reports average Homeowner Exemption savings of approximately **$950 per year**, a county average rather than a promise for one home. The Assessor’s Homeowner Exemption page also explains that exemptions appear on the second installment, which is why this bill is the place to confirm the line.
If the Homeowner Exemption line is missing, the bill is not showing that general owner-occupant reduction for the tax year. That can be especially important after a change in ownership. The seller’s exemption belongs to the seller’s circumstances; a new owner should not assume it transferred with the house. Once the Homeowner Exemption has been granted to the current owner, the Assessor says it auto-renews. A line that appeared before and has now disappeared therefore deserves a closer look as well.
Next, read the senior entries separately. The **Senior Citizens Homestead Exemption**, often shortened to Senior Homestead, reduces EAV by **$8,000** in Cook County. It is an age-based homestead exemption, and the Illinois Department of Revenue says Cook County requires an annual application with the Assessor. If that line is absent, the bill is not reflecting the $8,000 Senior Homestead reduction. The presence of a Homeowner Exemption does not fill that gap, and a missing Senior Homestead line tells you nothing by itself about the Senior Freeze.
The **Senior Freeze** is its own program. Rather than applying the Senior Homestead’s fixed EAV reduction, it freezes a qualifying property’s EAV at a base amount. It does not freeze the tax bill. A bill can still change when tax rates change or improvements are added. The Freeze also requires an annual filing, so a Senior Homestead line on the bill is not proof that the Senior Freeze is active.
The income year matters here. Under the Illinois Department of Revenue’s current PIO-74 exemption guidance, the maximum household income is **$75,000 or less for taxable year 2026 (payable 2027)**. That threshold belongs to taxable year 2026. The installment due October 1, 2026 is the tax year 2025 second installment, so do not use the new $75,000 cap to rewrite the eligibility rules for the bill already in your hand. It is the figure to carry into the 2026 Freeze filing that affects the bill payable in 2027.
This tax-year lag is one reason the senior lines are easy to misread. “Senior” may appear more than once, but one entry is the **Senior Citizens Homestead Exemption** and another is the **Senior Freeze**. The first is the $8,000 Cook County EAV reduction. The second holds qualifying EAV to a base year and has annual income and filing requirements. If you expected both and see only one, only the benefit named on the bill is visibly reflected.
Now separate an exemption problem from a valuation problem. When a qualifying exemption is missing from the 2025 second-installment bill, the Cook County Assessor points owners to the Certificate of Error process. That is the correction path for missing exemptions after the bill has arrived. If a Certificate of Error is approved and a refund is due, the Assessor directs owners to the Treasurer for refund timing. Approval and payment are separate events.
**“Property Over-Assessed”** belongs to a different process. It is the complaint type in the Cook County Board of Review’s online appeal flow. Use that assessment-appeal path when the dispute concerns the property’s assessed value, such as an estimated market value that the evidence does not support. The Illinois Department of Revenue states the boundary plainly: an assessment appeal challenges assessed value, not the tax bill. A missing exemption does not become an over-assessment complaint simply because it raises the amount due.
An owner can have both problems at once. The assessment may be too high while an expected exemption is also absent. In that case, correcting the exemption and challenging the valuation remain separate matters with separate records and deadlines. The Group 2 Board deadline on **Tuesday, September 29, 2026** does not turn an exemption correction into a Board complaint, and the October 1 due date does not extend an assessment-appeal window.
A pending Board appeal does not pause this installment. The Illinois Property Tax Appeal Board says taxes still come due during an appeal and should be paid on time; any overpaid taxes resulting from a later decision are refunded through the Treasurer. The Board’s filing guide likewise says its decisions are reflected in the following year’s tax bill. A filing made before September 29 cannot rewrite the bill due two days later.
Sources
- Cook County Treasurer, Important Dates
- Cook County Treasurer announcement, August 18, 2026
- Cook County Assessor, Homeowner Exemption
- Illinois Department of Revenue, Property Tax Exemption Information
- 35 ILCS 200/15-175
- 35 ILCS 200/15-170
- Illinois Property Tax Appeal Board, FAQ
- Censum FAQ
Sources accessed 2026-09-02.
FAQ
When is the second installment due?
Thursday, October 1, 2026 for tax year 2025. The Treasurer said 1.8 million bills would be mailed on or before September 1, 2026. The first installment was due Wednesday, April 1, 2026.
Is the $10,000 Homeowner Exemption $10,000 off my check?
No. It can reduce equalized assessed value by up to $10,000. That amount is a cap (the increase over 1977 EAV), not an automatic $10,000 off every parcel. The Assessor’s county average savings is about $950 a year, not a promise for one home.
What if an exemption is missing from this bill?
Use the Assessor’s Certificate of Error process. Do not file a Board complaint labeled Property Over-Assessed for a missing exemption. Approval of a Certificate of Error is not the same as a Treasurer refund.
Does Censum file the appeal for me?
No. Censum LLC is a data and analytics company, not a law firm and not a tax advisor. You file your own appeal.
Next step
Pay the October 1 installment, then read the exemption lines. Look up your PIN if you also need to check whether a valuation appeal is still open.
Censum LLC is a data and analytics company, not a law firm and not a tax advisor. You file your own appeal. Censum is independent and is not affiliated with Cook County or any government agency.