Multiply the current fair market value or appraised value by the 2017 Common Level Ratio of 65 to determine your correct assessed value. Compare the correct assessed value to the current real estate tax assessment you just located on the Delaware County website above. If the current assessed value is higher than the correct assessed value you should hire the Law Offices of Spadea & Associates, LLC to file a Real Estate Tax Assessment Appeal before August 1, 2016.