The valuation date: why last month's sale may be the wrong evidence
An assessment speaks to a specific date. Evidence has to speak to the same one.
Evidence that is perfectly good can be worthless because of its date. Assessments are made as at a specific statutory moment, and evidence from the wrong period is evidence about a different question.
What a valuation date is
Illinois assesses property as at 1 January of the tax year. The assessment is an opinion of what the property was worth on that date — not today, and not when the notice arrived.
Everything follows from that. A sale in March of the assessment year happened after the valuation date. A renovation completed in June did not exist on 1 January. A market collapse in autumn is next year's argument.
The lag people find confusing
Illinois property tax runs a year in arrears. The bill you pay this year is for last year's assessment. So there are commonly three different years in play at once:
| Year | What it is |
|---|---|
| Assessment year | The year whose 1 January is the valuation date |
| Appeal year | The year you file, usually the same as the assessment year |
| Billing year | The following year, when the bill arrives |
When you appeal, be explicit about which assessment year you are contesting. It is on the notice.
How this affects each kind of evidence
Sales. Closest to the valuation date is best. A sale six months either side is normally fine in a stable market; in a fast-moving one, an office may adjust for time, and you should say so before they do.
Appraisals. Must state the correct effective date. A refinance appraisal dated in September is not an opinion of value on 1 January, and an office is entitled to say so. If you commission one, instruct it for the assessment date explicitly.
Photographs of condition. Date them, and try to establish the condition existed on the valuation date. Photographs of damage repaired in March do not describe the property as it was in January.
Uniformity comparables. Immune to most of this, which is one of the argument's advantages — you are comparing assessments from the same year, all struck as at the same date.
The two situations this decides
You bought after 1 January. Your purchase price is evidence of value shortly after the valuation date, and normally strong. Note the gap and say so; do not pretend the dates coincide.
You improved the property during the year. Work completed after 1 January should not be in that year's assessment. If it is, that is a specific, checkable argument — and one that will legitimately appear in the following year.
The practical rule
Before submitting any piece of evidence, ask: does this describe the property, or the market, as at 1 January of the year I am appealing?
If not, either adjust for the difference and explain the adjustment, or leave it out. Evidence the office can dismiss on a technicality costs you more than the space it occupies — it invites doubt about everything else in the file.