Just bought? Your purchase price is the best evidence you will ever have
A recent arm's-length sale of the subject property is the strongest single item in an assessment appeal.
If you bought recently, you are holding the strongest piece of evidence this process recognises. Whether it helps or hurts depends entirely on which way it points, and the first thing to do is work out which.
Why a purchase price outranks everything
Every other argument reasons from what similar properties are worth. Your purchase is what a real buyer actually paid for this property, at arm's length, on a recorded deed.
The Cook County decision record shows how decisively offices treat it. The reason "this is the result of a sale analysis of your property" appears on 38,821 decisions, 100% of which were reductions. The reason "this is due to an analysis of the sale of the property" appears on 41,856, none of which were. The same evidence, cutting both ways.
The arithmetic to do first
- Take your assessed value and divide by your ratio — 0.10 in Cook, 0.3333 elsewhere in Illinois.
- Compare that implied market value against what you actually paid.
| Situation | What to do |
|---|---|
| You paid less than the implied value | File on market value. Attach the closing statement. This is close to decisive. |
| You paid about the implied value | Market value is not your argument. Check uniformity instead. |
| You paid more than the implied value | Do not file on market value. You would be supplying the evidence against yourself. |
The exemption that catches every new owner
Before any of that, check your exemptions. A homestead exemption does not transfer with the property. The previous owner's exemption came off when they left, and yours does not appear until you apply.
New construction is worse: the builder never claimed one, so there is nothing to inherit, and the first bill arrives with no exemption at all.
In Cook County the general homestead exemption removes $10,000 of equalised assessed value — worth around $750 a year at a mid-range rate. That is more than the median successful appeal, granted on an application rather than won on an argument. Do this first.
What "arm's length" means for you
Your sale only carries this weight if it was a genuine open-market transaction. If you bought from a relative, at a foreclosure, out of an estate, or as part of a larger deal, it is not evidence of market value — and if the assessor is using such a sale against you, saying so is a real argument.
The timing trap
Assessments are made as at a specific date, and there is a lag. A property bought in March may be assessed on a value set the previous January, and the assessment reflecting your purchase may not appear for a year or more.
Two consequences. If you bought below the implied value, file now rather than waiting — the current assessment predates your purchase and your evidence is new to them. And if you bought above it, expect the assessment to rise toward your price at the next reassessment regardless of what you do; that is the system working, not an error.
The order of operations
- File for your homestead exemption. Immediately, and any others you qualify for.
- Check the record against the property. New owners find errors constantly, because they have just had the place measured, surveyed and inspected.
- Do the implied-value arithmetic and decide whether your purchase helps or hurts.
- Choose the ground that fits — market value if you paid less, uniformity if you did not.