A Illinois property tax appeal is how you challenge an over-stated home value and bring your bill back down. You do not appeal the bill itself — a Illinois property tax appeal challenges your home’s assessed value, and if that value is higher than what your home would sell for, lowering it lowers your tax. In Illinois, appeals are heard by County Board of Review (then the Illinois Property Tax
Appeal Board / PTAB).
This guide covers who to file with, the deadline, how to build your case, and what happens at the hearing — all of it something you can do yourself, for free.
Illinois Property Tax at a Glance
| Who hears your appeal | County Board of Review (then the Illinois Property Tax Appeal Board / PTAB) |
| How Illinois reassesses | Property is assessed at 33-1/3% of market value (Cook County uses classification, about 10% for homes); a state equalizer then produces the EAV. General reassessment is every 4 years in most counties and every 3 years in Cook County. |
Verified from official state and county sources.
In This Illinois Guide:
How a Illinois Property Tax Appeal Works
Your Illinois property tax is your assessed value multiplied by your local tax rate. You cannot vote down the rate, but you can challenge the assessed value — and that is where most overpayment hides. If the assessor has your home valued higher than a fair market sale price, you are paying more than your share, and a Illinois property tax appeal is the fix. For context on how often
values are set here: Property is assessed at 33-1/3% of market value (Cook County uses classification, about 10% for homes); a state equalizer then produces the EAV.
General reassessment is every 4 years in most counties and every 3 years in Cook County. A Illinois property tax appeal is decided by County Board of Review (then the Illinois Property Tax Appeal Board / PTAB), which reviews your evidence and can lower an over-stated value. It is an ordinary, expected step — assessors handle these every year, and you do not need a lawyer to start one.
Think your Illinois bill is too high? Check in two minutes.
The Illinois Property Tax Appeal Deadline
This is the part people miss. The window for a Illinois property tax appeal is short and firm. In Illinois: File a complaint with your County Board of Review within 30 days after your township’s assessment list is published (the date varies by township/county; in Cook County the window opens township by township). If denied, appeal to the Illinois Property Tax Appeal Board (PTAB) within 30 days. Confirm your township’s
exact deadline with the assessor.
Mark the date the moment your assessment notice arrives — once the window closes, you generally wait until the next tax year to try again.
How to Prepare Your Illinois Property Tax Appeal
Your case is simply evidence that your home is worth less than its assessed value. The strongest proof is recent sales of similar homes near you that sold for less than your assessed value — three to five comparable sales make a solid packet. Also pull your property record card from the assessor and check it for plain errors: too much square footage, the wrong number of bedrooms or bathrooms,
a finished basement you do not have.
A factual error is one of the easiest wins, and it can carry a whole appeal on its own. A recent independent appraisal or photos of condition problems (a failing roof, foundation cracks) help too.
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After You File Your Illinois Property Tax Appeal
After you file with County Board of Review (then the Illinois Property Tax Appeal Board / PTAB), a Illinois property tax appeal usually gets a hearing where you present your evidence and the assessor presents theirs. Keep it factual and about value — comparable sales, not how much the bill hurts. Many appeals are settled or reduced at this stage. If you are not satisfied with the decision, most states
allow a further appeal to a state board or court; the notice you receive will explain that next step and its own deadline.
Whatever you do, keep paying the bill as billed while your appeal is pending, so you do not pick up penalties on top of everything else.
Don’t want to appeal your Illinois taxes yourself? A property tax appeal service can file everything for you and usually only charges if it wins — typically a share of what it saves you. It is one option; you can also appeal on your own for free.
Frequently Asked Questions
How do I file a Illinois property tax appeal?
File an appeal of your assessed value with County Board of Review (then the Illinois Property Tax Appeal Board / PTAB). File a complaint with your County Board of Review within 30 days after your township’s assessment list is published (the date varies by township/county; in Cook County the window opens township by township). If denied, appeal to the Illinois Property Tax Appeal Board (PTAB) within 30 days. Confirm your
township’s exact deadline with the assessor.
Bring comparable sales showing your home is worth less than its assessed value.
What is the deadline for a Illinois property tax appeal?
File a complaint with your County Board of Review within 30 days after your township’s assessment list is published (the date varies by township/county; in Cook County the window opens township by township). If denied, appeal to the Illinois Property Tax Appeal Board (PTAB) within 30 days. Confirm your township’s exact deadline with the assessor. Confirm the exact date with your local assessor.
Do I need a lawyer to appeal my Illinois property taxes?
No. Homeowners routinely file their own appeals for free. Evidence of value — comparable sales or an appraisal — matters far more than legal representation at the first level.
Will appealing make my assessment go up?
An appeal at the homeowner level is about proving your value is too high; the board’s job is to correct an over-assessment. Bring solid comparable sales so your case is clear.
Illinois Property Tax Sources & Data
- Tax Foundation — Property Taxes by State & County: taxfoundation.org
- U.S. Census Bureau (American Community Survey): census.gov/acs
- Lincoln Institute of Land Policy (property tax data): lincolninst.edu
Appeal details for Illinois on this page — which board hears appeals, the filing deadline, and the assessment
cycle — were verified from official Illinois state and county sources and last checked in July 2026. Deadlines and
procedures change and vary by county; confirm your exact date with County Board of Review (then the Illinois Property Tax Appeal Board / PTAB) or your county assessor before you
file.
More Property Tax Guides
- Property Tax Rates by State
- Property Tax by County
- Are You Overpaying? Over-Assessment Checker
- Property Tax Exemption Finder
Disclaimer: This guide is informational only and is not legal, tax, or financial advice. Know Property Tax is an independent educational resource. It is not a government agency, not a county assessor, and not a tax-appeal service. Property tax rates, bills, exemptions, and deadlines change over time and vary by county and property. Confirm anything that affects your taxes with your county assessor or a licensed professional before you act.