Property tax in Warren County, Illinois
In Warren County, the property tax bill comes from the Warren County Treasurer and Collector. The 2025 Pay 2026 bill is paid in 2 installments, and the next one is due October 30, 2026. You can look up and pay the bill on the county's own payment page. Taken from Warren County's own pages, checked September 23, 2026.
The median property tax bill in Warren County, Illinois is $1,903 a year, which is about 1.81% of the county's median home value of $105,000. That effective rate is about the same as the typical Illinois county (1.81%) and higher than the national median (0.81%). These are American Community Survey 5-year estimates (2024); your own bill depends on your home's assessed value and any exemptions.
Who sends the property tax bill in Warren County, and how do you pay it?
The bill comes from the Warren County Treasurer and Collector. The value it is based on is set by a separate office, the Warren County Supervisor of Assessments, with the township assessors, which is who to ask if the value looks wrong. For how to look up and pay the bill, go to the county's own payment information.
Township assessors value homes; the Supervisor of Assessments handles exemptions and takes Board of Review appeals. The exemptions on the county's pages (owner occupied, senior, senior assessment freeze, disability, veterans, home improvement, residential solar) are the state's programs. From January to May the Treasurer accepts prepayments of at least $50 and up to 90% of the prior year's bill, by check, money order or cash at the office; overpayments are refunded once bills are issued. Online payments go through Catalis, which charges 2.48% plus $1.25 on cards. Mobile homes get a separate bill, due July 15, 2026, with a late fee of $25 a month up to $100.
When are property taxes due in Warren County?
For the 2025 Pay 2026 bill, Warren County splits the bill into 2 payments, the first due July 30, 2026 and the last October 30, 2026. The next one due is the second installment, on October 30, 2026. Under state law an unpaid installment carries interest of 1.5% a month or part of a month starting the day after its due date. Certified letters go out to unpaid owners on November 24, 2026, after which personal checks are no longer accepted and a $10 fee is added. Delinquent taxes are published on December 23, 2026, and the annual tax sale is January 13, 2027 at 12:30 p.m. (an older line on the Treasurer's page still says the sale is held in October). After a sale, redemptions are made through the County Clerk.
| Payment | Due | Note |
|---|---|---|
| First installment | July 30, 2026 (passed) | Already past for this cycle. July 30, 2026 was a Thursday. Bills for 2025 taxes were mailed June 11, 2026, and participating banks took payments from that date. Under state law a mailed payment postmarked on or before the due date is on time. |
| Second installment | October 30, 2026 | October 30, 2026 is a Friday. The Treasurer's page also says due dates are set as close to June 1 and September 1 as possible each year, but its 2026 schedule shows July 30 and October 30. |
From Warren County's published schedule, checked September 23, 2026. If a date falls on a weekend or holiday, the county's own rules on the next business day apply.
Estimate the property tax on a home in Warren County
Enter a home's market value for a ballpark at Warren County's average effective rate of 1.81% (Census). The real bill depends on the home's assessed value, the millage where it sits and any exemptions.
Estimated property tax: $1,901 / year
Property tax in Warren County at a glance
| Measure | Value |
|---|---|
| Median annual property tax | $1,903 |
| Median home value | $105,000 |
| Effective tax rate | 1.81% |
| Typical Illinois county rate | 1.81% |
| National median county rate | 0.81% |
Effective rate = median real estate taxes paid divided by median home value. Source: U.S. Census Bureau, American Community Survey 5-year estimates.
How does Warren County compare in Illinois?
Among Illinois's 102 counties, Warren County has the 51st highest effective property-tax rate: 50 rank higher and 51 rank lower. That is near the middle for Illinois. Nationally, it ranks 142nd of 3135 US counties by effective rate. See every Illinois county ranked.
How much do homeowners in Warren County actually pay?
The median is only the middle bill. Across Warren County's 5,101 owner-occupied homes, 24.8% pay $3,000 or more a year in property tax, 45.1% pay at least $2,000, and 13.4% pay under $800. Another 2.8% report paying no property tax at all, which usually means an exemption covers the whole bill.
| Annual bill | Homes | Share |
|---|---|---|
| Under $800 | 683 | 13.4% |
| $800 to $1,499 | 1,052 | 20.6% |
| $1,500 to $1,999 | 923 | 18.1% |
| $2,000 to $2,999 | 1,035 | 20.3% |
| $3,000 or more | 1,266 | 24.8% |
| No property tax paid | 142 | 2.8% |
Owners with a mortgage pay a median of $1,825 and owners without one pay $2,056. Here the owners without a mortgage pay more, which can happen where long-held homes sit in the higher-value parts of the county. Census table B25103.
How does the Warren County property tax bill compare with local incomes?
The median property tax bill of $1,903 is about 2.4% of the median income of Warren County homeowner households, $78,190 a year. That compares two middles, so a retiree in a long-held home can pay a far larger share. 75.2% of Warren County's occupied homes are lived in by their owners; renters pay property tax too, just folded into rent.
Have property taxes gone up in Warren County?
Yes. The median bill went from $1,641 in 2015-2019 to $1,903 in 2020-2024, a 16% rise. Over the same span the median home value moved 25.1%, from $83,900 to $105,000. Bills rose more slowly than values, which is what assessment caps and falling millage rates do: the county is taxing a smaller share of each home's worth.
Two Census ACS 5-year periods with no survey years in common, in each period's own dollars. A change counts only if it exceeds the combined 90% margin of error.
Property tax in counties next to Warren County
Warren County borders 5 counties.
| County | Effective rate | Median bill | Median home value |
|---|---|---|---|
| Fulton County, IL | 2.14% | $2,289 | $107,200 |
| McDonough County, IL | 2.13% | $2,285 | $107,500 |
| Knox County, IL | 1.96% | $2,190 | $111,900 |
| Mercer County, IL | 1.96% | $2,878 | $146,700 |
| Warren County, IL (this county) | 1.81% | $1,903 | $105,000 |
| Henderson County, IL | 1.58% | $1,651 | $104,400 |
How is a home assessed in Warren County?
Illinois assesses homes at 33.33% of market value in every county, Warren County included. How Illinois assesses and reappraises homes.
Is there a homestead exemption in Warren County?
Yes. Illinois's General Homestead Exemption is $6,000 of equalized assessed value in most counties, $8,000 in counties next to Cook, and $10,000 in Cook County. That is the Illinois rule, and it applies in Warren County. Illinois's exemptions and relief programs in full.
Warren County does not add relief programs of its own beyond the Illinois ones (checked September 23, 2026).
How to appeal your Warren County property assessment
In Warren County you appeal to the Warren County Board of Review. The deadline: Within 30 days after the county publishes the year's assessed values in the newspaper. For 2025 values (the taxes billed in 2026), publication was October 29, 2025 and the deadline was November 28, 2025, so that window has closed. The county has not yet posted the publication date for 2026 values. Appeal forms are available from the Supervisor of Assessments office on the second floor of the courthouse in Monmouth. How to file. Checked September 23, 2026 against the official appeal rules.
How Illinois's appeal process works, including the next level if the first one turns you down.
Illinois rules from primary state sources, reviewed September 7, 2026; sources on the Illinois page.
Work out your own numbers
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How much house can I afford?
Your income, debts and down payment against the 28/36 rule lenders actually use, with Warren County's tax rate to hand.
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Mortgage calculator
Monthly payment with principal, interest, tax and insurance, plus what an extra payment saves you.
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Illinois income tax
Brackets, standard deduction and what Illinois actually taxes.
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Sales tax in Warren County
The other local tax: combined state and local rate for this county.
Sources
- Median real estate taxes paid and median home value for Warren County, Illinois: U.S. Census Bureau, American Community Survey 5-year estimates (2020-2024), tables B25103, B25077, B25102, B25119 and B25003; the five-year comparison uses the 2015-2019 estimates. Neighboring counties: Census county adjacency file.