What the 2027 Chicago Reassessment Actually Does to Your Assessment

Correction (October 3, 2026): An earlier version of this article said the Assessor's reassessment notice shows an assessed value rather than a market estimate, and that any later drop below the mailed value means an appeal reduced it. The notice carries the Assessor's estimated fair market value, the assessed value for residential property is usually 10% of that estimate, and the Board of Review can also lower an assessment on its own motion (Cook County Assessor; 35 ILCS 200/16-95).

Every three years, the Cook County Assessor takes a fresh look at property in a slice of the county and issues new assessed values. The county runs on a triennial cycle: the city of Chicago, the northern suburbs, and the southern suburbs each get their turn in rotation. Chicago's turn comes around again in 2027 — which means every Chicago parcel gets a new first-pass value that year, whether or not anything about the property changed.

If you own in the city, 2027 is the year your assessment resets. Here's what that actually means, without the jargon.

A reassessment is a reset, not an adjustment

In a non-reassessment year, your assessed value mostly carries forward. In your triennial year, the Assessor re-estimates it from scratch, using recent sales and property characteristics across your area. So the 2027 number isn't last year's value nudged up or down — it's a fresh determination. That's why reassessment years are the ones worth paying attention to: the biggest swings tend to land here.

Your notice shows a market value; your taxes use an assessed value

One thing that trips people up: your reassessment notice carries the Assessor's updated estimated fair market value, which is what the office believes properties like yours are worth (Cook County Assessor). Your assessed value, the amount used to calculate your property taxes, is a fraction of that: for residential property, usually 10% (Cook County Assessor). It's the number the county's math is built on. Neither one is a promise of what you could sell for, and knowing which number is which is the difference between reading the notice correctly and panicking at the wrong one.

The mailed value is only the first stage

The value you receive in 2027 is the mailed value — the Assessor's first pass. It is not final. From there it can move through an appeal pipeline: a certified value after an Assessor-level review, and a board value after the Board of Review. A later stage that lands below the mailed value means the assessment was reduced at that stage. An appeal is one way that happens; the Board of Review can also change an assessment on its own motion (35 ILCS 200/16-95). We walk through those three stages in detail in how to read your block's appeal pipeline — for now, the point is that the reassessment starts the clock, and you have moves after the mailed notice arrives.

What Civic Worth shows for your parcel

On a Chicago parcel report, the tax section shows your assessed value across the county's stages — mailed, certified, and board, for the years on record — and where your parcel sits in the triennial cycle. When there's an open appeal window on record, it's flagged; when there isn't one on record, the report says so plainly rather than guessing. It sits in the same report as the rest of your parcel's record. For the county's own view, the Treasurer's Cook County Property Tax Portal also gathers tax and appeal information by PIN.

What to do in a reassessment year

• Read the mailed notice as a starting point, not a verdict. It's stage one of three.
• Check whether the reset looks reasonable against what you know about your block. A sharp jump is exactly the kind of thing an appeal exists to address.
• Know your window. Appeal periods open by township and close fast. Watch for the window on your parcel rather than assuming you've missed it.

See your own number

Start at your community area — the Loop, Near North Side, Lake View, or any of Chicago's 77 — or search your address on the Chicago hub. Every address resolves to its 14-digit Cook County PIN and, from there, to the assessment history the 2027 reassessment will reset. Look before the notice arrives, and you'll know exactly what changed.

Sources

• Illinois Compiled Statutes, 35 ILCS 200/9-220 (Cook County reassessment districts)
• Cook County Assessor, Assessment & Appeal Calendar
• Cook County Assessor, Overview of How Appeals Work
• Cook County Assessor, How Residential Property Is Valued
• Cook County Assessor, Assessed Values (Cook County open data)
• Cook County Board of Review, Frequently Asked Questions
• Illinois Compiled Statutes, 35 ILCS 200/16-95 (Board of Review powers)
• Cook County Treasurer, Cook County Property Tax Portal
• City of Chicago data portal, Boundaries - Community Areas