How to appeal property taxes in Illinois

Chicago — Cook County has no single 2026 appeal deadline; each township has its own last-file date. See the township table for current dates, plus forms and savings math.

DuPage 2026 appeal deadlines run 30 days after township publication; dates not posted yet. Learn exactly where to file, evidence, hearings, savings.

Kane County has no single 2026 deadline — each township's window closes 30 days after its assessment-change publication date; confirmed dates run from July 9 through at least Sept. 18 (Rutland), with some townships still TBD. Get the forms, filing address, evidence rules, and a savings example.

Lake County has no single 2026 deadline — each township gets its own window, 30 days after that township's assessment-roll publication; the earliest confirmed 2026 dates were in late August, with other townships following later in the year. Learn SmartFile steps, evidence, hearing choices, exemptions, and savings math.

McHenry County has no single 2026 deadline — each township gets its own window, 30 days after that township's assessment list is published. Confirmed 2026 dates ran from Aug. 6 onward; check your township's current date before assuming you've missed it. See the exact forms, evidence rules, filing addresses, hearings, exemptions, and savings math.

Joliet — Will County’s 2026 Board of Review complaint deadline (Sept. 14) has passed. Forms, filing steps, fees and evidence tips for the next cycle, with sources.

Rockford — Winnebago County's 2026 appeal deadlines (Sept. 4-5) have passed. Get the forms, filing steps, and evidence tips for the next window.