Free guide
Cook County Property Tax Appeal Basics
Everything a Cook County homeowner needs to know before appealing, in about five minutes. Read it here or download the PDF.
Download the free PDF1. How your tax bill is built
- The Cook County Assessor estimates your home's market value. For homes, the assessed value is 10% of that market value.
- Your tax bill depends on your assessed value, the state equalizer, your exemptions, and local tax rates.
- You can't appeal tax rates, but you can appeal the assessed value. A lower assessment usually means a lower bill.
2. The three places to appeal
- Cook County Assessor: the first stop. Each township has a short filing window, usually about 30 days, once its reassessment notices are mailed.
- Cook County Board of Review: a second, separate chance later in the year, again by township.
- Illinois Property Tax Appeal Board (PTAB): after a Board of Review decision, if you still disagree.
- You can file with the Assessor and the Board of Review in the same year. Filing is free and can be done online.
3. The argument that wins most often
- "Lack of uniformity": your home is assessed higher per square foot than similar homes in your neighborhood.
- Good comparables share your neighborhood code and property class, and have similar size and age.
- Recent sales of similar homes can also show your assessed market value is too high.
4. Signs you may be over-assessed
- Your assessment jumped much more than your neighbors' did.
- County records list the wrong square footage, bathrooms, or features.
- Similar homes on your block are assessed lower per square foot.
- Your home sold recently for less than the Assessor's estimated market value.
5. A simple filing checklist
- Find your 14-digit PIN on your tax bill or assessment notice.
- Check your township's filing window. Missing it means waiting for the next office or the next year.
- Gather 3 to 10 comparable homes with their PINs, square footage, and assessed values.
- File online with the right office, keep your confirmation number, and watch for the decision.
See if your home is over-assessed
Our free check compares your assessment with similar homes nearby in 30 seconds. If you look over-assessed, the $79 DIY kit gives you the comparables, the exact numbers to enter, and step-by-step filing help.