Illinois property tax deadlines

214 sourced dates. 102 of 102 Illinois counties have at least one.

Illinois bills property tax a year behind, so 2025 taxes are paid in 2026. Each county treasurer sets its own due dates every year, most often two installments around June 1 and September 1, while Cook and a few other counties bill the first installment early at 55% of last year's tax. Late installments cost 1.5% interest a month. To fight your assessment, file with the county board of review by its deadline (usually 30 days after the assessment list comes out), and if you lose there, you have 30 days from the decision's postmark to go to the state Property Tax Appeal Board.

Paying the bill Paying late Appealing your value Homestead exemption

Own in two states: Florida and Illinois, Arizona and Illinois