How to appeal your Cook County property taxes yourself

There are two levels of appeal

Cook County gives every homeowner two separate chances to challenge an assessment in the same tax year:

1. The Assessor’s office (CCAO). When your township is reassessed, the Assessor mails a notice and opens a filing window — typically about 30 days — during which you can file an appeal directly with their office, online, for free. This is a desk review; an analyst compares your evidence against county data.

2. The Board of Review (BoR). A separate, independent body. You can file here whether or not you appealed to the Assessor first, and — critically — you can file here even after a loss at the Assessor level, in the same tax year. Townships open on a rolling schedule across the year, each with its own roughly 30-day window and a separate evidence deadline shortly after.

Both levels are free, both are handled through online portals, and both let you represent yourself.

Deadlines are set by township, and they are hard

Unlike a lot of government deadlines, Cook County’s appeal windows don’t bend. Miss your township’s window at the Assessor’s office, and your next chance is the Board of Review’s window for that township later in the year. Miss that one too, and you’re waiting until your township comes up again. That’s exactly why Morganwell shows you the specific deadline for your township when you search your property, rather than a generic county-wide date.

The three grounds that actually win

Cook County appeals succeed on a fairly small set of arguments. The three most common for homeowners:

Assessed above comparable neighbors (lack of uniformity). The Illinois constitution requires property to be taxed uniformly within its class. If your home’s assessed value per square foot is meaningfully higher than similar homes nearby — same class, similar size and age, same neighborhood — that’s grounds for a reduction. This is the most common residential argument, and it’s covered in depth in what makes a strong uniformity appeal.

Recent purchase below the assessed value. If you bought your home recently in an arm’s-length sale — not a sale between relatives, not a foreclosure — for less than the value the county is implying, that sale price is strong evidence on its own. The county requires you to disclose recent sale details as part of any appeal regardless of which ground you argue.

Property-record errors. Sometimes the county simply has the wrong facts — incorrect square footage, an extra bathroom that doesn’t exist, the wrong building class. These factual corrections can often be requested at any time, not just during the appeal window, though correcting a record error doesn’t always change your assessed value on its own.

What the county asks you to submit

Two rules come up constantly in Cook County’s own appeal instructions:

A current photo of your home. The Board of Review asks for a color photo of the front of your property, taken within the past 12 months, submitted along with your evidence.

Disclosure of any recent sale. If your home sold within the past few years — even if you’re not using the sale as your main argument — the county requires you to disclose the sale documents and, if the sale price is very different from the assessed value, a brief explanation of why.

Do you need a lawyer? Usually not

If you own your home in your own name, you can file and represent yourself at both the Assessor’s office and the Board of Review — what’s called filing pro se. This is completely normal: the county’s own published appeal data shows homeowners who file themselves win regularly in Cook County.

The exception is ownership structure, not skill. If your home is held in an LLC, a corporation, or certain kinds of trusts, the Board of Review generally requires an attorney to file on the entity’s behalf. If you own your home individually or in a simple land trust in your own name, you’re almost certainly fine to file yourself.