Property taxes are one of the largest recurring bills most homeowners pay — and one of the few you can actually challenge. In Illinois, where rates are among the highest in the country, the stakes are real. Yet the system assumes you'll never question it, and most people don't.
Here are five checks you can do today, mostly with records you already have, to figure out whether you're paying more than your fair share.
1. Compare your assessed value to what your home would actually sell for
Your tax bill starts with an assessed value. In Illinois, residential property is assessed at roughly one-third of its fair market value, so multiply your assessed value by three to get the county's implied market value. Then ask the real question: could you sell your home for that today?
If the implied value comes out to $330,000 but comparable homes near you are closing at $295,000, that gap is the heart of an appeal. Mass appraisal works in bulk and lags the market — a cooling market is one of the most common reasons assessments drift too high.
2. Check your home's "comps"
Assessors are supposed to value similar homes similarly. Find three to five homes near you that are alike in size, age, and condition, and look at their recent sale prices and assessments (both are public record). If near-identical neighbors are assessed for noticeably less than you, that's a uniformity argument — and it's one of the most common grounds for a reduction in Illinois.
3. Audit the township's record of your home
Pull your property's record from your township assessor. You're looking for plain factual errors:
- Square footage larger than your home actually is
- A bathroom, bedroom, or garage you don't have
- A finished basement that's actually unfinished
- Land or lot dimensions that are wrong
These errors are surprisingly common, and they're the easiest wins — you're not arguing opinion, just correcting a fact.
4. Account for condition the model can't see
Mass appraisal never visits your home. It doesn't know about the foundation crack, the roof at end of life, the kitchen that hasn't been touched since the '90s, or the new development backing your fence. Each of these legitimately lowers market value — and each is invisible to the model that set your assessment.
5. Look at the trend
Did your assessment jump far more than homes actually appreciated in your area? A double-digit assessment increase in a flat market is a flag worth pulling on.
If two or more of these checks point the same way, the odds are good that you're over-assessed — and that an appeal is worth filing.
What to do if you find a gap
You have two options. You can assemble the evidence, learn your township's deadline and the Will County Board of Review's forms, and file the appeal yourself — it's doable, just tedious. Or you can start with our free estimate: we pull the records and comparable sales and show you what you'd likely save before you decide anything.