Estimate the proration credit
Enter the last full-year tax bill, the proration percentage your contract uses, and the dates. The accrual start is usually January 1 for a calendar-year proration.
Enter your figures to calculate.
Closing calculators
Property Tax Proration Calculator
Estimate the property tax credit at a Cook County closing. Because taxes are billed in arrears, the seller credits the buyer for tax that accrued during the seller period but will be billed later. This is a planning tool, not closing advice.
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Why Cook County prorates in arrears
Cook County collects property tax for a year after that year ends. At closing the seller has lived in the home for part of the current year but the bill has not arrived yet, so the seller credits the buyer for that accrued tax. Contracts often prorate at 100 to 110 percent of the last full-year bill to cushion against increases.
Cook County installment schedule
| Installment | Amount | Typical timing |
|---|---|---|
| First installment | 55 percent of the prior year bill | Mailed late January, commonly due about April 1 |
| Second installment | Balance after new assessment and rates | Mailed and due in late summer or early fall |
Because the bill arrives after the year it covers, the proration credit at closing keeps each party responsible for taxes during their own period of ownership.
How property tax proration works at a Cook County closing
Proration splits the property tax bill between the seller and the buyer based on how much of the period each one owned the home. In Cook County, where taxes are paid in arrears, the seller has not yet received a bill for the current year at closing, so the seller credits the buyer for the tax that accrued from the start of the accrual period to the closing date. The buyer then pays the full bill when it arrives.
The credit is usually figured as a percentage of the last full-year bill. Many contracts use 100 to 110 percent to allow for assessment and rate increases that have not been billed yet. The exact percentage, the accrual start date, and the method are negotiable in the purchase contract, so confirm them with your attorney and title company.
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Proration FAQs
Why does the seller credit the buyer for taxes?
Cook County bills property tax in arrears, meaning the bill for a year arrives after that year. At closing the seller owes tax for the part of the year they owned the home, but the bill has not come yet, so the seller credits the buyer who will pay the full bill later.
What proration percentage should I use?
Contracts commonly use 100 to 110 percent of the last full-year bill. A higher percentage protects the buyer against assessment and rate increases that are not yet billed. The exact figure is negotiated in the contract.
When are Cook County property taxes due?
The first installment, set by law at 55 percent of the prior year bill, is mailed in late January and is commonly due around April 1. The second installment is mailed and due in late summer or early fall once new assessments and rates are set.
Is the proration on this tool the final figure?
No. It is an estimate. The binding proration is calculated by the title company or attorney at closing using the agreed percentage, the exact dates, and the actual bills. Confirm before signing.
This calculator is general information for Chicago-area owners, buyers, and investors. It is not legal, tax, lending, appraisal, or brokerage advice, and rates or rules can change. Verify figures with the appropriate professionals before money moves or documents are signed. Proration terms are negotiated in the purchase contract and finalized by the title company or attorney at closing.