When you qualify for the Over 65 Exemption, Williamson County will subtract $25,000.00 from the appraised value of your property before calculating your taxes. The school district will also subtract $10,000.00 from the appraised value before calculating your taxes. After those exemptions are applied, the dollar amount you pay for Williamson County, ISD, and Williamson County FM/RD taxes will freeze. All other taxing entities provide exemptions based on voter approved amounts.