Check the County.

The homeowner's reading room

Cook County property tax appeal evidence checklist

Start with the reason you believe the assessment is wrong, then gather records that address that reason. This checklist helps homeowners organize a residential appeal file. It is a preparation worksheet, not a county form or a requirement to submit every document listed.

By Check the County, operated by Embento LLC. Reviewed .

1. Identify the property, year, and filing office

Save your assessment notice and county property record. Put the full 14-digit PIN, address, township, and assessment year at the top of your folder. If a property has multiple PINs, identify which parcels your evidence concerns. Use the PIN guide if you are unsure.

The Assessor and Board of Review have separate filing windows. Check the official calendar linked from your township page, then record both the filing and evidence deadlines. The Assessor's 2026 rules require supporting documents by the appeal deadline; follow the receiving office's current instructions rather than assuming you can add them later.

2. Match your documents to your argument

  • Market value: organize comparable recorded sales with PINs, prices, dates, and property facts. Explain important differences, not just why the prices are lower.
  • Recent purchase: gather your closing records and sale context. Our recent-purchase guide explains why a sale price needs context.
  • Assessment uniformity: keep assessment comparisons separate from sales comparisons. A neighbor's lower tax bill alone does not establish unequal assessment; see our neighbor comparison guide.
  • Incorrect property facts: identify the disputed entry and supporting record, such as a measured plan. Use the property-record correction checklist.
  • Condition issues: organize dated photos and relevant supporting reports. Explain the issue and when it existed; do not assume a repair cost equals a dollar-for-dollar assessment reduction.

Check the office's current rules for required forms, photographs, appraisal requirements, and other documentation. The Board of Review FAQ links its residential evidence guidance.

3. Make the file easy to review

Use descriptive filenames such as “01-assessment-notice.pdf” and “02-sales-comparison.pdf.” Keep a short document index explaining what each attachment supports. This is an organizational suggestion, not an official naming rule.

Before uploading, open each file and check that pages are readable, correctly oriented, and complete. Keep the original documents in a separate folder. The Assessor's rules require redaction of non-public personal information, including financial account and Social Security numbers. Follow its redaction guidance without removing information needed to evaluate the appeal.

Example: document the comparison, not just the conclusion

Instead of writing “My assessment is too high,” record the county's value, the assessment year, the comparison you investigated, and the attached records supporting your request. If a comparable home has a different size or condition, explain that limitation. Do not invent an adjustment to make the figures fit.

5. Confirm submission and keep a copy

Review the uploaded attachments and save the confirmation, document list, and submission date. A folder of evidence or a property check on this site does not file an appeal. Follow up with the receiving office if the submission status is unclear.

If your window has closed, review the missed-deadline guide before choosing another process. Avoid assuming that a message or uploaded document reopens a closed filing period.

Official sources reviewed October 31, 2026: Assessor appeal rules and Board of Review rules. These govern your filing; this worksheet helps you prepare.

General information for public-record research, not legal, tax, or appraisal advice. Verify filing requirements with the office handling your request.