Illinois Property Tax Appeal Board: How to Lower Your Property Taxes in Illinois
If your Illinois assessment notice arrived and the number looks too high, you have the right to challenge it — without hiring anyone. Illinois gives homeowners two distinct paths: a local appeal to your county's Board of Review, and if that doesn't go your way, an appeal to the Illinois Property Tax Appeal Board/PTAB, the state-level body that reviews residential assessments. This guide walks you through both.
Step 1 — Start With Your County Board of Review
Every Illinois county has a Board of Review that accepts complaints about over-assessed property values. This is your first and often fastest option. The process typically looks like this:
- Check your assessment notice for the appeal deadline — it varies by county and township and changes each year. Missing it means waiting until the next assessment cycle.
- Get your county's complaint form from the Board of Review website or office. Cook County's form differs from downstate counties.
- Gather comparable sales (comps) — recent sales of similar homes nearby that support a lower market value. Three to five solid comps are usually enough.
- Submit the form and your evidence by the deadline. Many counties accept filings online, by mail, or in person.
- Attend a hearing if one is scheduled, or accept the board's written decision.
Always verify the exact deadline and form requirements directly with your county Board of Review — rules differ across Illinois's 102 counties and can change annually.
Step 2 — Escalate to PTAB if the Board of Review Denies You
If the Board of Review reduces your assessment but not enough — or denies your complaint entirely — you can file a petition with PTAB. A few things to know before you do:
- PTAB has its own petition form and filing deadline, which is separate from the Board of Review deadline. The clock typically starts after the Board of Review issues its final decision.
- PTAB hearings are more formal than local board hearings. You'll present evidence — comps, an appraisal, or a uniformity argument — to a hearing officer.
- A uniformity appeal argues your assessment is higher than comparable properties nearby, even if it isn't above market value — a common and effective argument in Illinois.
- PTAB decisions can take months to over a year. If you win, the reduction is retroactive to the tax year in question.
Check PTAB's official site (ptab.illinois.gov) for current petition forms, instructions, and filing windows. Do not rely on third-party summaries for deadlines — confirm directly with the agency.
What Evidence Actually Works in Illinois
Illinois boards respond to two main arguments: overvaluation (your home is assessed above its market value) and uniformity (your home is assessed higher than similar nearby properties). Comparable sales data supports both.
Strong evidence includes recent arm's-length sales of homes with similar square footage, age, style, and condition within your neighborhood or township. A licensed appraisal carries the most weight at PTAB, though comps alone often succeed at the Board of Review level. Photographs of property condition, repair estimates, or a recent purchase price below the assessed value can also help.
Don't Overlook Exemptions Before You Appeal
Illinois offers several exemptions that reduce your assessed value before the tax rate applies — homestead, senior citizen homestead, senior freeze, veteran, and disability exemptions. If you're not claiming every exemption you qualify for, contact your county assessor — it's the fastest way to lower your bill without a formal appeal.
Is It Worth Appealing on Your Own?
The Board of Review process costs nothing to file and can often be completed without a hearing. Many homeowners who bring three to five solid comparable sales walk away with a reduction. PTAB is more involved but still accessible without an attorney — PTAB publishes plain-language guides for self-represented petitioners.
Appeal companies and tax attorneys operate in Illinois on a contingency fee — typically a percentage of your first-year savings. That may be worth it for a complex PTAB case or a substantially over-assessed property. For a straightforward overvaluation with solid comps, the DIY route at the Board of Review is very achievable. A reduction is never guaranteed regardless of who files.
What Illinois Homeowners Actually Pay: Average Rates by County
Illinois does not tax market value directly. Assessments are expressed as equalized assessed value, and the tax rate is applied to that figure — which is why Illinois rates look enormous next to states that tax full value. The Department of Revenue publishes the average rate for every county each year. For 2024 the statewide average on residential property was 7.94%, down from 8.22% the year before. The median across the 102 counties was 7.64%.
| County | Residential average rate 2024 | 2023 | Rank of 102 |
|---|---|---|---|
| Cook County | 8.25% | 8.37% | 22 |
| DuPage County | 6.67% | 6.95% | 85 |
| Lake County | 8.57% | 8.99% | 12 |
| Will County | 7.88% | 8.40% | 45 |
| Kane County | 7.66% | 8.26% | 51 |
| McHenry County | 7.97% | 8.69% | 39 |
| Statewide average | 7.94% | 8.22% | — |
The spread is wider than the metro picture suggests. Across all 102 counties the residential average ranged from 4.56% in Hardin County to 10.36% in McDonough County. Cook ranks 22 and Lake ranks 12, so the two counties that dominate the conversation about Illinois property tax are both above the 7.64% median but neither is near the top. A high rate does not by itself mean your assessment is wrong; it means an assessment error costs you more.
How Much Boards of Review Actually Change: The Statewide Picture
Before any tax bill is calculated, the county board responsible for reviewing assessments finishes its revisions, and the Department of Revenue publishes each county's total assessed value both before and after that stage. The comparison below is the net effect on the whole assessment base — it is not an appeal success rate, because the board's revisions include corrections in both directions and property it adds or removes for reasons unrelated to any appeal. What it does show is where boards move value, and by how much.
| Area | All property | Residential | Commercial |
|---|---|---|---|
| Cook County | -6.32% | -1.17% | -13.79% |
| Collar counties | -0.98% | -0.09% | -4.26% |
| Rest of state | +1.13% | +1.39% | +0.64% |
| Statewide | -1.49% | +0.15% | -7.01% |
Read the commercial column. Statewide, boards of review ended 2024 with commercial assessments 7.01% lower than the assessing officer set them, while residential assessments finished +0.15% — essentially unchanged in aggregate. In Cook County the commercial figure is 13.79%. Commercial owners appeal through counsel as a matter of routine and they move real money doing it. That asymmetry is the honest argument for filing as a homeowner: the mechanism works, it is simply used far more systematically by the other side.
The aggregate also hides what happens to individual homes. Cook County publishes the outcome of every case, and there the residential numbers are clear: the Board of Review reduced 39.9% of the 490,231 residential appeals it decided for tax year 2024. An aggregate that barely moves is made up of many individual reductions offset by increases elsewhere in the base.
Illinois Property Tax Appeals: Common Questions
Why are Illinois property tax rates over 7% when other states charge under 2%?
Because the rate is applied to equalized assessed value, not market value. Outside Cook County assessed value is set at one third of market value, and an equalization factor is then applied to bring counties onto a common footing. A 7.94% rate on one third of value is not comparable to a 2% rate on full value. Compare the dollar amount on your bill, never the percentage.
Do I appeal to the county or to the state?
The county first. Assessment complaints are heard at county level, and in Cook County you can also go to the Assessor before the review stage. Only once the county has issued its decision does the Illinois Property Tax Appeal Board or circuit court become available to you.
What is the equalization factor and can I challenge it?
It is a multiplier the Department of Revenue certifies for each county so that assessment levels are comparable statewide. You cannot challenge it in your own case — it applies to the whole county. What you can challenge is your own assessed value before the factor is applied.
Is the deadline the same in every Illinois county?
No. Each Board of Review sets its own filing period, generally running for about 30 days after the county publishes its assessment list, and the publication date differs county by county and year by year. There is no single statewide date to rely on.
Does appealing help if my assessment did not change?
It can. The question is not whether your value rose but whether it is correct relative to comparable properties. An assessment that has been too high for several years stays too high until someone contests it.
How much does an Illinois appeal cost?
Filing with a Board of Review is free in every county. Costs arise only if you hire an attorney or appeal service, which commonly works for a share of the first-year reduction, and in some counties for a flat fee.
Sources. Average rates and assessment revisions are taken from the Illinois Department of Revenue, Property Tax Statistics 2024 — Table 8, Average Tax Rates, and Table 18, Local Assessments by Class before and after Revisions by County Board of Review. Ranks and the median are computed across the counties listed in Table 8. The Cook County case figures come from the Cook County Board of Review's published appeal decision data.