Property tax in Grundy County, Illinois

Who sends the property tax bill in Grundy County, and how do you pay it?

The bill comes from the Grundy County Treasurer (the county collector). The value it is based on is set by a separate office, the Grundy 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 set the first value, the county Supervisor of Assessments reviews it and handles exemptions, and the Treasurer sends one bill that carries the taxes of every local district the property sits in, such as schools, cities, townships and fire districts. You can pay online, by mail, by phone at 815-324-6390, at the drop box outside the Sheriff's Department, at participating local banks, or in person at the courthouse in Morris. Online and in-office card payments carry a 2.5% fee ($3 minimum) and electronic checks a $1.50 fee; the payment processor keeps these, not the county. Mobile home taxes are billed separately, due August 28, 2026. Taxes sold at a tax sale are redeemed through the County Clerk, not the Treasurer.

When are property taxes due in Grundy County?

Every due date for the 2025 Payable 2026 bill has passed, and Grundy County had not posted the next cycle's dates when we checked on September 23, 2026. If that bill is still unpaid, the late-payment rules below apply to it. Counties usually repeat the schedule, but confirm the new dates on your next bill. For the 2025 Payable 2026 bill, Grundy County splits the bill into 2 payments, the first due June 26, 2026 and the last September 4, 2026. Late payments are charged a penalty of 1.5% a month, as Illinois law requires. After October 1, a $10 publication fee is added to every delinquent parcel. Payments made on or after October 1 must be cash, cashier's check, credit card or money order; personal and business checks are not accepted after that date. Electronic checks are accepted through October 15 and credit cards through October 31. Unpaid taxes go to the county's tax sale; last year's sale was held November 4, 2025, and the county has not yet posted the date of this year's sale.

From Grundy 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 Grundy County

Enter a home's market value for a ballpark at Grundy County's average effective rate of 1.99% (Census). The real bill depends on the home's assessed value, the millage where it sits and any exemptions.

Property tax in Grundy County at a glance

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 Grundy County compare in Illinois?

Among Illinois's 102 counties, Grundy County has the 31st highest effective property-tax rate: 30 rank higher and 71 rank lower. That is on the higher side for Illinois. Nationally, it ranks 91st of 3135 US counties by effective rate. See every Illinois county ranked.

How much do homeowners in Grundy County actually pay?

The median is only the middle bill. Across Grundy County's 15,319 owner-occupied homes, 80.4% pay $3,000 or more a year in property tax, 89.2% pay at least $2,000, and 4.7% pay under $800. Another 2.3% report paying no property tax at all, which usually means an exemption covers the whole bill.

Owners with a mortgage pay a median of $5,828 and owners without one pay $4,549. Owners who have paid off a home have usually held it longer, and in states that cap how fast an existing owner's assessment can rise, long-held homes carry lower assessed values. Census table B25103.

How does the Grundy County property tax bill compare with local incomes?

The median property tax bill of $5,420 is about 5.1% of the median income of Grundy County homeowner households, $105,842 a year. That compares two middles, so a retiree in a long-held home can pay a far larger share. 74.4% of Grundy 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 Grundy County?

Yes. The median bill went from $4,182 in 2015-2019 to $5,420 in 2020-2024, a 29.6% rise. Over the same span the median home value moved 36.3%, from $199,300 to $271,700. 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 Grundy County

Grundy County borders 5 counties.

How is a home assessed in Grundy County?

Illinois assesses homes at 33.33% of market value in every county, Grundy County included. How Illinois assesses and reappraises homes.

Is there a homestead exemption in Grundy 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 Grundy County. Illinois's exemptions and relief programs in full.

Grundy County does not add relief programs of its own beyond the Illinois ones (checked September 23, 2026).

How to appeal your Grundy County property assessment

In Grundy County you appeal to the Grundy County Board of Review. The deadline: For the 2026 assessments (the bills paid in 2027), assessment notices were mailed on September 23, 2026, and the deadline to file an appeal is Monday, October 26, 2026. An appeal delivered in person must reach the Assessment Office by 4:30 p.m. that day; an emailed appeal, with the signed complaint form and all evidence, must be sent by 11:59 p.m.; a mailed appeal must be postmarked by that date. Starting with 2026, the county no longer mails a notice to owners whose value changed only by the equalization factor or the state's farmland values; those owners can check their new value on the county's online assessment inquiry. 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

• How much house can I afford?

  Your income, debts and down payment against the 28/36 rule lenders actually use, with Grundy County's tax rate to hand.

• Mortgage calculator

  Monthly payment with principal, interest, tax and insurance, plus what an extra payment saves you.

• Illinois income tax

  Brackets, standard deduction and what Illinois actually taxes.

• Sales tax in Grundy County

  The other local tax: combined state and local rate for this county.