For good cause shown, the chief appraiser may extend the application filing deadline once for a period not to exceed. The general deadline for filing an exemption application is before May 1.What is the Deadline? Your application must be submitted between January 1 and April 30 of the tax year. A completed exemption application form must be filed with the district prior to May 1st. I'm going to show you how to file your homestead exemption in Dallas County Texas. The typical deadline for filing a county appraisal district homestead exemption application is between January 1 and April 30.