How to file a Board of Review appeal in Illinois
The form, the evidence, the copies, and the order to do them in.
Filing a property tax appeal in Illinois is a paperwork exercise, not a legal proceeding. Most residential appeals are decided on documents alone, without anyone appearing anywhere. Here is the sequence.
Before you file: is there an argument?
Twenty minutes of arithmetic decides whether the rest is worth doing.
- Implied market value. Total assessed value ÷ your ratio (0.10 in Cook, 0.3333 elsewhere). Would you list at that price? If clearly not, you have a market-value argument.
- Assessment per square foot. Improvement assessed value ÷ floor area. Compare against four or five comparable neighbours. If yours is conspicuously higher, you have a uniformity argument.
- The record. Check floor area, year built, bedrooms, basement, garage, lot size and class code against reality. An error here is the strongest and simplest argument available.
If none of the three produces anything, filing is unlikely to be worth your evening — and the county-wide base rates are sobering: across 1.79 million Cook County decisions, 23% produced a reduction.
The steps
1. Find your deadline
Thirty days from publication of your township's roll, and it varies by township. It is on your notice and on the county's schedule.
2. Get the form
From your Board of Review's website — in Cook, from the Assessor first and the Board separately. Most counties now offer online filing, which is faster and timestamps your submission.
3. Choose your ground and say which it is
Do not file a general complaint that your taxes are too high. State the ground:
- Uniformity — comparable properties are assessed lower per square foot.
- Market value — the implied value exceeds what the property would sell for.
- Factual error — the record is wrong in a specific, stated way.
- Recent sale — you bought it recently, at arm's length, for less than the implied value.
4. Assemble evidence that matches the ground
| Ground | What to attach |
|---|---|
| Uniformity | 4–6 comparable parcels: PIN, address, class, floor area, improvement assessed value, and the per-square-foot figure for each |
| Market value | Recent arm's-length sales of genuinely similar properties, or an appraisal |
| Factual error | Evidence of the true figure: survey, plans, closing documents, photographs, a permit record |
| Recent sale | Closing statement or deed showing price and date |
5. State the value you are asking for
Do not leave this to the office. If your comparables sit at a median of $14 per square foot of improvement and your building is 1,800 square feet, you are asking for an improvement assessment of $25,200 — plus your unchanged land figure. Show that arithmetic. An appeal that says "too high" without naming a number invites the office to decide how much relief you deserve.
6. File before the deadline, and keep proof
Online filing gives you a confirmation. Keep it.
What happens next
Most residential appeals are decided on the documents. You may be offered a hearing; for a clean uniformity case with good comparables it is often unnecessary. Decisions typically arrive weeks to months later, and the change appears on a subsequent bill rather than as a refund.
The mistakes that cost people the appeal
- Comparables that are not comparable. Four tight ones beat twenty loose ones. One obviously unsuitable comparable gives the office a reason to doubt the whole set.
- Dividing the total by floor area. Uniformity runs on the improvement assessment. Using the total penalises you for your own lot.
- Arguing about the tax rate. The office has no authority over it.
- Arguing you cannot afford it. Not a ground. Hardship relief exists, but it is a different application.
- Missing the deadline — see above, and it is the most common failure of all.