Cook County property tax appeal deadlines: how the 2026 calendar actually works

There is no single property tax appeal deadline in Cook County. Each of the county's 38 townships gets its own filing window with the Assessor, roughly 30 to 40 days long, on a rolling schedule that runs through the year. Your deadline depends entirely on which township your home sits in, and it is probably not the same as your neighbor two suburbs over.

That staggered calendar is the single biggest reason homeowners miss their chance to appeal. This page explains how the system works and where to find your township's live deadline.

Why there are 38 different deadlines

Cook County is too large to process every appeal at once, so the Assessor's office opens townships in sequence. When your township opens, you can file an appeal with the Assessor for free. When it closes, that window is gone until next year, though a second, separate window at the Board of Review comes later.

A few things about the calendar that surprise people:

• The window belongs to your TOWNSHIP, not your city. Municipal borders and township borders do not match. Des Plaines, for example, is mostly Maine Township. If you are not sure which township you are in, a free address check at parcel-vue.com tells you in seconds.
• Windows open through the year on the county's schedule, and the exact dates shift from year to year. A date that was right last cycle can be wrong this cycle.
• The county does not send you a reminder when your window opens. The reassessment notice arrives whenever your area is revalued; the appeal window is on you to track.

The reassessment cycle underneath it

Cook County revalues property on a three-year cycle, one part of the county at a time. In 2026, the south and west suburban townships are being reassessed, which means homeowners there are receiving new reassessment notices and their appeal windows carry extra weight: the value set now is the base for the next three years of bills.

If you got a reassessment notice this year, the moment to compare your new value against similar homes is when the notice lands, not when the first bill built on it arrives. By the time the bill shows up, the appeal window that could have corrected it is often long closed.

Where the live deadlines are

Every township has its own page with the current window status, the close date, and the local numbers, updated from county data:

• Cicero Township
• Elk Grove Township
• Lake View Township
• Maine Township
• Palos Township
• Stickney Township

For any other township, or if you do not know your township, run the free check at parcel-vue.com: it identifies your township and shows its live deadline alongside whether your home looks over-assessed.

The list above comes from the same county-synced data that powers the township pages, refreshed daily. Whenever you are reading this, it reflects the calendar as it stands now.

What happens if you miss your window

Missing the Assessor window is not the end of the year's options. The Board of Review, a separate county body, opens its own window for each township later in the year, and it takes a fresh look with the same kind of evidence. Plenty of appeals that lost at the Assessor, or never filed there, succeed at the Board of Review.

Miss both, and you are waiting for next year's calendar. The windows come around annually, which is why putting your township's dates on your own calendar is worth the two minutes.

Why this matters at all

ParcelVue analyzes all 1,077,564 residential parcels in Cook County against the Assessor's own records. 250,478 of them are assessed above comparable homes nearby, and the average assessment gap on those homes is $10,424. An assessment above comparable homes is exactly what an appeal is designed to correct, and the appeal calendar is the only thing standing between most of those homeowners and a look at the evidence.

Two facts worth knowing before you decide anything: filing an appeal with the Assessor is free, and an appeal can never raise your assessment. The outcome is your value goes down or stays the same.

Check where your township stands

Type your address at parcel-vue.com. In about two minutes you will see whether your home looks over-assessed against comparable homes, which township you are in, and the live deadline that applies to you. If your home comes back fairly assessed, it says so, and doing nothing is the right move.