Prepaying Illinois Property Taxes by December 31, 2017

By Terry Cicero

UPDATED: 12/20/17

With tax reform on the horizon, many taxpayers will benefit from prepaying property taxes before year-end. A great number of taxpayers will no longer itemize deductions in 2018 due to the nearly doubling of the standard deduction (to $24,000 for married).

For more information on why someone may want to prepay property taxes (and also why you may want to accelerate charity), view this article: Capture Tax Savings by Paying Certain Deductions Before Year-End. Also, check out this example: Case 1

Even if you plan to itemize your deductions in 2018, you will be limited to a combined $10,000 deduction for state and property tax, so prepaying property tax may make sense for you. See this example: Case 2

In both cases above, the taxpayers above are not subject to AMT (Alternative Minimum Tax). When you are subject to AMT, prepaying property taxes generally yields no income tax benefit.

Each taxpayer’s situation is different, so please check with your tax advisor on whether prepaying makes sense for you.

Property Tax Prepayment Instructions for DuPage and Surrounding Counties


DuPage County

• Mail your check payment to the DuPage County Treasurer, 421 N. County Farm Road, Wheaton, IL 60187. Please indicate your PIN on the check and mark your envelope “Prepayment” for proper processing. You can pay up to 105% of prior year tax.

Kane County
• Fill out the attached application for prepayment and remit payment to the Kane County Treasurer.

Cook County
• Visit the Cook County website to pay your Cook County Bill Now. Please make sure to have the PIN ready. The prepayment amount is already calculated for you to pay. You can only prepay the first installment.

Kendall County
• As of December 22, 2017, Kendall County is accepting prepayments from taxpayers for an amount equal to one installment rounded up to the nearest $100. Payments are due by Friday, December 29, 2017.

Will County
• Prepayments can be made by mail or in person. Check to “Will County Collector”; include PIN on check. They may assess a processing fee of up to $2. Mailing address: Will County Treasurer’s Office 302 N Chicago St, Joliet, IL 60432.

Lake County

• Checks made out to the Lake County Treasurer can be mailed between December 1 and December 29 only. Payments cannot be higher than current year’s tax amount and the PIN needs to be noted on the check as well as “Pre-Payment” on the check and envelop. Mail to Lake County Treasurer, 18 N County Street Room 102, Waukegan, IL 60085. They will only refund taxes if prepayment is higher than the amount due.

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