The single most common question about Cook County appeals is "when's the deadline?" — and the honest answer is that it depends on where you live. The county doesn't run one appeal season for everyone. It opens appeals township by township, on a rolling calendar, and each township's window is a firm cutoff. This guide explains that system so you can find your own date and act in time.
What's on this page
Deadlines are set by township, not county-wide
Cook County has 38 townships, and the Assessor opens each one for appeals at a different time. When your township opens, a clock starts: homeowners typically get about 30 days to file (some recent windows have run somewhat longer). When it closes, it's closed — these are hard deadlines with essentially no extensions.
Practically, that means a neighbor two towns over might be past their deadline while yours hasn't opened yet, or vice versa. Don't rely on what a friend in another suburb tells you about "the deadline" — find your township's dates.
How to find your township's window
Two reliable sources, and it's worth checking both:
- Your reassessment notice. In a year your township is reassessed, the county mails you a notice with your new proposed value — and the appeal deadline is printed right on it. Keep that notice.
- The official Cook County Assessor assessment calendar. It lists every township's open and close dates and is updated as the year progresses. Because dates can shift and future townships post with little notice, check the calendar close to when you plan to file rather than trusting a date you saw months ago.
A note of caution: third-party sites and aggregators sometimes list Cook County deadlines that don't match the county's own calendar. When they conflict, the Assessor's official calendar wins. Verify there before you rely on a date.
The triennial reassessment cycle
Cook County reassesses property on a three-year cycle, split into three regions. Each region gets reassessed once every three years, on this rotation:
| Region | Most recent reassessment |
|---|---|
| City of Chicago | 2024 |
| Northern suburbs | 2025 |
| South & West suburbs | 2026 |
Why this matters for deadlines: a reassessment year is when your value is most likely to change — often upward — and it's the year the appeal question is most pressing. If you're in a South or West suburb, 2026 is your reassessment year. That doesn't mean you can only appeal in a reassessment year; Cook County lets you appeal annually, every year your township's window is open. But the reassessment year is the one to watch most closely.
If you missed the Assessor's deadline
Missing your Assessor window is not the end of the road for the year. Cook County has a second, independent venue: the Board of Review. It reviews assessments separately from the Assessor, opens its own township windows on a different schedule, and lets homeowners file pro se for free — just like the Assessor.
So the sequence many homeowners follow is simply: file at the Assessor if your window is open; if you missed it, or if the Assessor says no, file at the Board of Review when it opens your township. Our step-by-step appeal guide walks through both venues.
Why it pays to check early
You don't have to wait until your window opens to figure out whether you even have a case. The public assessment data that supports an appeal is available year-round. Checking early means that when your township does open, you already know whether it's worth filing — and you're not scrambling against a 30-day clock to gather comps.
Check your home now — free, any time of year
VineWorth compares your Cook County assessment to similar homes using public county records, so you know where you stand before your window opens. If you don't have a case, we'll say so — no charge.
Check my home →Free check · No card required · You file your own appeal, free at the county
Common questions
When is the property tax appeal deadline in Cook County?
There's no single county-wide date. Appeals open township by township on a rolling schedule, and each window is a hard deadline — typically around 30 days once your township opens. Find your township's dates on your reassessment notice or the official Cook County Assessor assessment calendar.
How do I find my township's deadline?
Check your reassessment notice (the deadline is printed on it) and the Assessor's official assessment calendar, which lists every township's open and close dates and is updated regularly. Dates can move, so verify on the official calendar near when you plan to file.
Can I appeal every year, or only in a reassessment year?
You can appeal annually — every year your township's window is open — not just in your reassessment year. The reassessment year (once every three years for your region) is simply when values change most and the appeal question is most urgent.
What if I missed my window?
You can still appeal at the Cook County Board of Review, a separate agency with its own township schedule. Missing the Assessor's window doesn't remove your options for the year — see the appeal guide for how the two venues fit together.
This guide is general educational information about the Cook County property-tax appeal process, not legal or tax advice. Appeal windows, dates, and procedures are set by Cook County and change frequently — always verify against the official Cook County Assessor assessment calendar and the Cook County Board of Review before relying on any date. VineWorth is an automated self-help document-preparation service; it is not a law firm and does not file appeals on homeowners' behalf. Homeowners file their own appeals, in their own name. Filing is free at the county, and no appeal outcome is guaranteed.