Illinois property tax appeal · $49 flat · keep 100%
How to appeal your Illinois property taxes
Illinois assesses most property at 33⅓% of fair cash value (35 ILCS 200/9-145), but Cook County classifies instead and assesses residential property at 10% of market value (Cook County Code ch. 74, §74-63). You file a written complaint with your County Board of Review, on your township's schedule in Cook, or within 30 days of the published assessment list elsewhere. If the board denies relief, you may appeal to the state Property Tax Appeal Board (PTAB) within 30 days.
Free to check in 30 seconds. No signup, no credit card.
See how the Illinois process worksIllinois appeal deadline
Deadlines varyNo single statewide date, Cook County runs township by township; other counties are 30 days after the assessment list is published
Illinois has no single statewide deadline. In Cook County, complaints are filed township by township on the dates printed in the township's reassessment notices (35 ILCS 200/16-115), so your window depends on where you live and reopens each reassessment cycle. In every other county, the deadline is on or before 30 calendar days after your township's assessment list is published (35 ILCS 200/16-55). Check your county Board of Review's calendar for your township's dates.
The Illinois appeal process, step by step
1. Watch for your township's reassessment notice
In Cook County, townships are reassessed on a rolling three-year cycle and each mails its own notice; your filing window runs from that notice (35 ILCS 200/16-115). Outside Cook, watch for your township's assessment list to be published.
2. File a complaint with the Board of Review
Cook County: file by your township's deadline. Every other county: file on or before 30 calendar days after the assessment list is published (35 ILCS 200/16-55). There is no filing fee. Note that the statute calls this a complaint, not an appeal, at this stage.
3. Build your evidence
Two arguments work. Overvaluation: recent sales of similar homes show your market value is too high, which you prove by a preponderance of the evidence. Lack of uniformity: comparable properties are assessed lower per square foot than yours, which under Kankakee County Board of Review v. Property Tax Appeal Board, 131 Ill. 2d 1 (1989), requires clear and convincing evidence.
4. Board of Review decision
The Board of Review reviews your complaint and may correct your assessment (35 ILCS 200/16-95 in Cook). It issues a written decision.
5. PTAB or Circuit Court (optional)
If you disagree, you may appeal to the state Property Tax Appeal Board within 30 days of the board's written decision (35 ILCS 200/16-160). Alternatively, you may pay under protest and file a tax objection in Circuit Court after exhausting the Board of Review (35 ILCS 200/23-5, 23-10).
Illinois counties
County-specific filing notes for Illinois's largest markets. More counties added as we expand.
Cook County
Chicago
Chicago's county, and the only Illinois county that classifies: residential property is assessed at 10% of market value rather than the statewide 33⅓%. Complaints are filed township by township on the dates in each township's notice, so there is no single Cook deadline.
DuPage County
Wheaton
Chicago's western suburbs, assessed at the statewide 33⅓% of fair cash value. File within 30 days of your township's published assessment list.
Lake County
Waukegan
Among the highest effective property tax rates in the country. File within 30 days of your township's published assessment list.
Will County
Joliet
Chicago's southwest suburbs. The Board of Review complaint window opens when your township's assessment list is published and runs 30 days.
Illinois property tax appeal FAQ
What is the property tax appeal deadline in Illinois?
There is no single statewide date. Cook County files township by township on the dates printed in each township's reassessment notice (35 ILCS 200/16-115). Every other county runs 30 calendar days from publication of the assessment list (35 ILCS 200/16-55). Check your County Board of Review's calendar.
Why is my Cook County assessment only 10% of my home's value?
Cook is Illinois's only classifying county. Under the Cook County Classification Ordinance (ch. 74, §74-63), residential property is assessed at 10% of fair market value. The rest of Illinois uses the statutory 33⅓% of fair cash value (35 ILCS 200/9-145). A low assessment ratio does not mean you are not over-assessed, what matters is whether your market value is right and whether similar homes are assessed the same.
What happens if the Board of Review denies my complaint?
You may appeal to the state Property Tax Appeal Board (PTAB) within 30 days of the board's written decision (35 ILCS 200/16-160), or pay under protest and file a tax objection in Circuit Court (35 ILCS 200/23-5).
Are you missing a Illinois exemption?
Exemptions cut your bill before any appeal even starts, and most homeowners never claim all the ones they qualify for. Answer four questions:
We're building Illinois's county data now
Your Illinois protest guide is ready above. We're loading Illinois's county-level comparable-sales data so you can check your exact over-assessment in one click. Drop your email and we'll notify you the moment it's live.
We'll only email you about Illinois property tax data, no spam.
See if your Illinois home is over-assessed
Free check, no signup. If you want the protest kit after that, it's $49 flat, pre-filled and ready to sign and submit. No contingency, no recurring charge, 30-day refund. You keep 100% of your savings.
Check my address free →