Your property tax assessment may be too high.

Enter your address. ParcelProof compares your assessment with similar properties nearby and tells you whether an appeal is worth filing — using your county's own published records, with the arithmetic shown.

Free to check. No card, no commitment. If there is a case worth making, the completed filing packet is $10.99 — one payment, no subscription, refunded on request.

A real ParcelProof result

Park Ridge, Cook County · 1,564 sq ft · measured against 653 comparable parcels

Assessed at
$83,000
Per square foot
$53.07
Neighbourhood median
$32.01
Above the median
66%
Supported by comparables
$50,064
Assessment reduction indicated
$32,936

An assessment figure, not a tax bill. What that reduction is worth in tax depends on your equalisation factor, exemptions and local rates — your notice is the authority.

See exactly how this was calculated →

New: the other half of the argument

Illinois lets you challenge an assessment two ways. The check above argues uniformity — your assessment against comparable properties. The Sales Reality Check argues market value: whether your home is assessed above what homes like it have actually sold for, from 333,255 recorded Cook County sales.

It runs a full IAAO sales-ratio study — level of assessment, COD, PRD — and prints every sale it used so you can check the work.

Run a free sales-ratio study →

How it works

  1. Enter an address. The search is free and takes seconds.
  2. We compare it against nearby properties of similar size and class, drawn from published county assessment records.
  3. You get a verdict — worth filing, or not. "Not worth filing" is the answer we return most often, and it is a useful one.
  4. If there is a case, the $10.99 packet contains the comparables, the arithmetic and the completed form for your jurisdiction. You file it.

What ParcelProof is, and is not

Built by Zappfin LLC in Illinois, on roughly five million normalised Illinois parcel records. We show the comparables and the working so you can check them, rather than asking you to trust a prediction.

We are not a law firm. We do not file for you, do not appear before a board, and guarantee no outcome. In Cook County an individual may represent themselves; property held by an LLC or corporation generally needs an Illinois attorney. More about us · Legal · Deadlines by state