Assessments can be appealed at the Cook County Assessor’s office, the Cook County Board of Review, the Illinois Property Tax Appeal Board (PTAB) and Cook County Circuit Court. Appeals to the Assessor and the Board of Review may only be filed at specific times during the year depending on which township your property is located. You can find out whether your township is open for appeal by going to the web sites for each of those offices. Appeals to the PTAB can only be made if you have previously filed an appeal at the Board of Review for the tax year in question and must be made within thirty days of the date on the letter you receive from the Board informing you of their decision. If you choose to file a case at the circuit court, you automatically forego the opportunity to appeal at PTAB and vice-versa.