Illinois Property Tax Appeal:
How to Fight Your Over-Assessment
In Illinois, 49% of appeals succeed with an average savings of $1,100/year. Yet fewer than 5% of homeowners ever file. Here’s how to do it — and how Tax Ghost generates your formal appeal letter for $24.99.
Illinois Property Tax Appeal — Key Facts
How to Appeal in Illinois
Check your assessment notice
Your county assessor mails assessment notices — usually in spring. The notice shows your assessed value and the appeal deadline. In most states you have 30–90 days from the notice date.
Gather comparable sales
Find 3–5 similar properties in your neighborhood that sold recently at prices below your assessed value. Use Zillow, Redfin, or your county recorder's public records. The more recent and similar the sales, the stronger your case.
File your formal appeal
In Illinois, you file with the County Board of Review (Cook County: Board of Review or Assessor). File written appeal with the County Board of Review. Cook County has a separate Assessor's Office appeal process. Evidence must include comparables from the same assessment year. File before 30 days after assessment published in local paper.
Present your evidence at the hearing
Show up with your comparables. Be calm and factual. You don't need a lawyer. Appeals boards are accustomed to homeowners representing themselves. Simply demonstrating that comparable properties sold for less than your assessment is often enough to win a reduction.
Expert tip for Illinois
Illinois only allows comparables from properties sold within the same assessment year. Cook County appeals are high-volume — file online and be specific.
Get your Illinois appeal letter — $24.99
Formal appeal letter citing 35 ILCS 200/16-55, addressed to the County Board of Review (Cook County: Board of Review or Assessor). Evidence checklist and filing instructions included. PDF delivered in 60 seconds.
Free scan → pay only if you want the letter
Frequently Asked Questions
How do I appeal my property tax assessment in Illinois?
In Illinois, you file an appeal with the County Board of Review (Cook County: Board of Review or Assessor). The deadline is 30 days after assessment published in local paper. You can file yourself — no attorney required. File written appeal with the County Board of Review. Cook County has a separate Assessor's Office appeal process. Evidence must include comparables from the same assessment year.
What is the property tax appeal success rate in Illinois?
Approximately 49% of property tax appeals in Illinois result in a reduced assessment. The average annual tax savings for successful appeals is around $1,100.
What evidence do I need to win a property tax appeal in Illinois?
The strongest evidence is 3–5 recent comparable sales in your neighborhood with sale prices below your assessed value. An independent appraisal is also very effective. You can find comparables on Zillow, Redfin, or your county recorder's public records.
What law governs property tax assessments in Illinois?
Property tax assessments in Illinois are governed by 35 ILCS 200/16-55. Under this law, property must be assessed at fair market value — defined as what a willing buyer would pay a willing seller in an arm's-length transaction.
Do I need a lawyer to appeal my property taxes in Illinois?
No. The vast majority of successful Illinois property tax appeals are filed by homeowners without attorneys. You simply need to file your appeal before the deadline and present evidence (comparable sales) showing your property's market value is lower than the assessed value.