Evidence Checklist

Organize the proof before you file.

A Cook County property-tax appeal is easier to review when the deadline, PIN, property record, comparable evidence, and filing proof are in one place.

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Source Checked
May 5, 2026

This guide summarizes official Assessor and Board of Review guidance, but filing rules and windows can change. Verify the official source before submitting anything.

1. Confirm the deadline and filing office

  • - Check the current township window before starting.
  • - Confirm whether you are filing with the Assessor, the Board of Review, or preparing for a later stage.
  • - Save the official deadline source with the date you checked it.

2. Verify the property record

  • - Confirm the correct address, PIN, unit, class, building square footage, and property characteristics.
  • - Look for factual errors such as wrong square footage, wrong property description, or missing condition context.
  • - For condos, make sure the correct unit/PIN is selected before comparing values.

3. Organize comparable-property evidence

  • - Use similar properties in the same neighborhood and classification where possible.
  • - Keep addresses, PINs, assessments, sale dates, sale prices, and photos together.
  • - Avoid cherry-picking only low values; the evidence should explain why the properties are actually comparable.

4. Gather documents that explain value or condition

  • - Recent purchase documents can matter if the sale was arm's length and below the current county value.
  • - Photos, repair estimates, or condition notes can help explain deferred maintenance or damage.
  • - Redact sensitive personal and financial information before uploading documents.

5. Save filing proof

  • - Submit before the official deadline.
  • - Save the confirmation email, docket number, uploaded evidence list, and any receipt or screenshot.
  • - Keep a copy of what you filed so later review or follow-up is not guesswork.