What to do after a Cook County reassessment notice
The reassessment notice gives you a new proposed value and a short window to challenge it. Before deciding whether to appeal, verify the property facts, compare the assessment to similar homes, and note the township deadline.
Start with your property—not a generic tax estimate.
Enter the address or PIN from the reassessment notice.
Free to check first. No credit card required.
1. Check the filing deadline first
The Assessor opens appeals by township. During a reassessment year, owners generally have roughly a month after the notice to file, but the actual last-file date shown by Cook County controls.
Check how Cook County appeal deadlines work →2. Verify the property characteristics
Look for material errors in the County record: building square footage, property class, age, exterior construction, basement, garage, baths, or other characteristics that can affect valuation and comparable selection.
3. Compare your assessment with similar homes
A reassessment increase by itself does not prove the assessment is wrong. A stronger question is whether comparable homes are being assessed more favorably after accounting for physical differences.
How a uniformity appeal uses comparable properties →4. Preserve the Assessor opportunity
If the Assessor window is open and you want both review opportunities, file there first. The Board of Review comes later as a separate review. Board pre-registration does not replace a missed Assessor filing.
2026 reassessment context
Cook County says the south and west suburban townships are the scheduled reassessment area for 2026. The County also notes that updated values can lag the reassessment mailing by about one business day online, which is why a brand-new notice may briefly arrive before every public-data surface has refreshed.
Check whether the current Cook County data gives you a case worth filing.
The notice and official County calendar control the filing deadline. Simple Tax Appeal is independent and is not affiliated with Cook County.