Cook County Property Tax Appeal: 2026 Township Deadlines

Last checked September 5, 2026 against the official sources linked below. This guide covers filings during 2026; the assessment roll or resulting tax bill may belong to a later year. Check the current official notice before filing.

Cook County's south and west suburbs are in the 2026 reassessment cycle. Your property identification number, township and assessment notice determine the relevant Assessor window. A city name or mailing address alone is not enough to choose it.

The dates above are the Assessor's last filing dates. Later townships remain pending as of this guide's verification date. Do not substitute an anticipated month for a published filing deadline.

For a market-value argument, show why comparable transactions support a lower value for the property. For a uniformity argument, examine the assessment treatment of genuinely similar properties. A low assessment on a dissimilar neighbor is not automatically a useful comparison.

Verify the subject's property class, building area, age, construction and condition before comparing it with other homes. An incorrect record can make an apparently sophisticated comparison unreliable.

The Board of Review has its own township openings, deadlines and filing rules. An Assessor filing does not submit a Board case or reserve that later deadline. Check the Board calendar independently if you intend to pursue that route.

The Board's rules allow an individual owner to appear on their own behalf or use an attorney. A nonattorney appeal service should not promise to represent an owner at the Board. Before appointing assistance for an Assessor filing, confirm that the representative meets that office's requirements.

A successful appeal changes an assessment; the final tax bill also depends on equalization, exemptions and tax rates. Do not turn an assessment reduction percentage into a guaranteed bill reduction percentage.

Check homeowner exemptions separately, save the appeal acknowledgment and monitor requests for additional evidence. Confirm the scope of any service agreement so you know who is responsible for each filing and hearing.