What is the property tax rate in Illinois?
The property tax rate in Illinois averages 1.88% of a home’s market value, the Tax Foundation’s 2026 effective rate based on 2024 Census data for owner-occupied homes. On a $400,000 house that is about $7,520 a year, and only New Jersey matches it.
Apartment buildings don’t get a separate state rate. Each parcel pays the combined rate of every district it sits in, such as the county, township, school district, park district and library, and those combined rates differ widely between Lake Forest and North Chicago, or between Chicago and the south suburbs. The statewide average is a starting point, and the parcel’s own bill is the number a buyer will underwrite.
How Illinois property tax is calculated
An Illinois tax bill equals the equalized assessed value (EAV), minus any exemptions, times the composite tax rate. EAV is market value times the assessment level times the equalization factor, which Illinois calls the multiplier.
The rate comes last. Each district certifies a levy, the dollars it wants to raise, and the county clerk divides that levy by the district’s total EAV to get its rate. Add up the rates of every overlapping district and you get the composite rate on the bill. Because the rate is backed out of the levy, a higher assessment on your building mostly shifts a bigger share of a fixed levy to you, rather than raising the total collected, especially in districts under the tax cap law.
- Market value x assessment level = assessed value
- Assessed value x multiplier = equalized assessed value (EAV)
- (EAV - exemptions) x composite rate = tax bill
How assessed value is set outside Cook County
Outside Cook County, non-farm property is assessed at 33 1/3% of fair cash value under Illinois law. If a county’s assessments drift away from that level, the Illinois Department of Revenue applies a county equalization factor so the median level comes back to 33 1/3%.
Assessors revalue everything on a four-year cycle, known as the quadrennial reassessment, and adjust values in the years between. Kane County, for example, publishes its 33.33% level and quadrennial schedule on its assessments site. For a rough check outside Cook, divide the composite rate by three to estimate the tax as a share of market value. A DuPage parcel at the county’s 6.6967% average rate pays about 2.23% of market value before exemptions.
Cook County property tax for apartment owners
Cook County assesses residential property, including apartment buildings, at 10% of market value and most commercial property at 25%, under its classification ordinance. The state then applies a multiplier to bring Cook’s overall level up to the statewide 33 1/3%.
For tax year 2025, billed in 2026, the Department of Revenue set the final Cook County multiplier at 3.0300, down from the 2024 final of 3.0355. The tentative 2025 figure announced in April 2026 was 2.8683, so the final number moved after the Board of Review finished its work. In practice, a Chicago apartment building’s EAV is about 30.3% of its assessed market value (10% times 3.0300), while a store or office building at 25% carries about 75.8%.
Cook County reassesses on a three-year cycle, one region at a time. The City of Chicago was reassessed in 2024, the north suburbs in 2025, and 2026 is the south and west suburbs’ year. Each township gets reassessment notices followed by a last file date for appeals, roughly six weeks later. Proviso Township’s notices went out September 14, 2026, with a last file date of October 27, 2026.
| Cook County item | Figure | Source |
|---|---|---|
| Residential level (including apartments) | 10% of market value | Cook County Assessor |
| Commercial level | 25% of market value | Cook County Assessor |
| Final multiplier, tax year 2025 | 3.0300 | IDOR, June 2026 |
| Final multiplier, tax year 2024 | 3.0355 | IDOR |
| Reassessment cycle | Every 3 years by region | Cook County |
| 2026 reassessment region | South and west suburbs | Cook County Assessor calendar |
Does Illinois reassess property when it sells?
No. An Illinois sale does not reset the assessment the way a California sale does. Values change at the general reassessment, every four years outside Cook and every three years in Cook.
Sales still feed the system. The Department of Revenue uses recorded sale prices in its sales-ratio studies to set multipliers, and assessors use them to revalue at the next cycle. An assessor may also correct an assessment that is plainly wrong at any time. For a buyer, the practical question is when the next reassessment hits, and how far the current assessed market value sits below the price being paid.
Is there a cap on property taxes in Illinois?
There is no cap on an individual building’s assessment or tax bill in Illinois. The Property Tax Extension Limitation Law (PTELL), the tax cap law, limits districts instead.
In Cook, the collar counties and other counties that adopted it, PTELL limits a non-home-rule district’s total extension growth to the lesser of 5% or the prior year’s CPI, plus new construction and any increase voters approve. Home-rule units such as Chicago are not bound by it. So a reassessment can raise your bill sharply even while the district’s total levy grows slowly, because your share of the levy changed.
Illinois property tax rates by county
Illinois county rates are published as a percentage of EAV, not market value, so they look much higher than the 1.88% effective rate. The Department of Revenue’s statewide county table was not retrievable for this page, so the table uses the rates each county clerk publishes for its own area, labeled by year. The Cook County Clerk has since released its 2024 and 2025 tax rate reports, which we could not open, so the Cook rows below are older and will not match a current bill. Check the newest Clerk report for your parcel’s tax code before you rely on a Cook rate.
To compare with market value, divide outside-Cook rates by about three. In Cook, multiply the rate by about 0.303 for apartments. Chicago’s 6.995% composite for 2023 becomes roughly 2.12% of market value before exemptions, while the 10.986% sample rate for a typical south suburb becomes about 3.3%, which is why apartment owners in the south suburbs feel the bill most.
| County and area | Published rate (% of EAV) | Year and basis |
|---|---|---|
| Cook: typical south suburb | 10.986% | 2023 sample rate from the Clerk’s 2023 report, via the Civic Federation |
| Cook: north and northwest suburbs | 8.825% | 2022 average composite, Cook County Clerk |
| Cook: City of Chicago | 6.995% | 2023 composite for most Chicago parcels, Clerk’s 2023 report, via the Civic Federation |
| Lake: North Chicago (highest) | 11.859% | 2025 predominant rate, Lake County Clerk |
| Lake: Lake Forest (lowest) | 5.776% | 2025 predominant rate, Lake County Clerk |
| Kane: countywide | 7.09% | 2024 total tax extended / total assessed value, Kane County Clerk |
| DuPage: countywide average | 6.6967% | 2025 average tax rate, DuPage County Clerk |
How to appeal property taxes in Illinois
You appeal first to the local assessor or county Board of Review, then to the state Property Tax Appeal Board (PTAB) or the circuit court. The windows are short, so watch for the published assessment list or your reassessment notice.
Outside Cook, a complaint usually goes to the county Board of Review within 30 days after the assessment list is published. White County’s board rules are one example, and each county sets its exact date. In Cook, you file with the Assessor by your township’s last file date, then with the Cook County Board of Review when its window for your township opens. A Board of Review decision can be taken to PTAB within 30 days of the board’s written notice.
| Step | Where | Deadline |
|---|---|---|
| First appeal, outside Cook | County Board of Review | Within 30 days of the assessment list publication (varies by county) |
| Board-proposed increase, outside Cook | County Board of Review | Within 10 days of the notice |
| First appeal, Cook | Cook County Assessor | Township last file date, about 6 weeks after notices |
| Second appeal, Cook | Cook County Board of Review | When the township’s board window opens |
| State appeal | Property Tax Appeal Board | Within 30 days of the Board of Review notice |
Property tax exemptions for apartment buildings
Illinois homestead exemptions apply only to owner-occupied homes, so a rental building usually has none. The main break for apartments is Cook County’s Affordable Housing Special Assessment Program.
The program, under 35 ILCS 200/15-178, applies to buildings with seven or more units that are newly built or substantially rehabbed. It cuts assessed value by 25% under Tier 15, where 15% to 34% of units rent at or below 60% of area median income, or by 35% under Tier 35, where at least 35% of units do. Terms run 10 years and can be renewed up to 30. A graduated tier applies in low-affordability communities. Applications for 2026 were due September 5. A buyer of an enrolled building should confirm the remaining term, because losing the incentive raises the tax.
Worked example: property tax on a $2 million Illinois apartment building
Take a 24-unit building in Chicago that the Assessor values at $2,000,000. Its assessed value is $200,000 at the 10% level, and its EAV is $606,000 after the 3.0300 multiplier. At the 6.995% Chicago composite rate for tax year 2023, used here as a stand-in for the parcel’s actual and newer rate, the yearly tax is about $42,390, or 2.12% of value.
The same $2,000,000 building in DuPage County would carry an EAV of about $666,667 at 33 1/3%, and at the 2025 countywide average rate of 6.6967% the tax would be about $44,645.
Now the sale. Say the Assessor carried the Chicago building at $1,600,000 and a buyer pays $2,000,000. The sale itself changes nothing, but if the 2027 city reassessment moves the value to the price, the bill rises from about $33,912 to $42,390, a jump of $8,478. That comes straight out of NOI. At a 6% cap rate, $8,478 of lost NOI is about $141,300 of value, which is why buyers in Cook underwrite the next triennial and not the current bill.
| Line | Before reassessment | After reassessment |
|---|---|---|
| Assessor market value | $1,600,000 | $2,000,000 |
| Assessed value at 10% | $160,000 | $200,000 |
| EAV at 3.0300 | $484,800 | $606,000 |
| Tax at 6.995% | $33,912 | $42,390 |
| Change in yearly NOI | -$8,478 |
Selling an Illinois apartment building to Skyline
Skyline buys apartment buildings with five or more units in Illinois, including Chicago, suburban Cook and the collar counties. We buy directly, close on your timeline, and can work inside 1031 deadlines. If a pending appeal or a coming reassessment is weighing on your price, tell us early and we will price the building with the tax figures in front of us.
