Exemption applications can be downloaded from here. Bought a primary residence within the past year in Texas?It's time to file for your Texas Homestead Exemption. Exemption applications must be filed with your local assessor's office. See our Municipal Profiles for your local assessor's mailing address. In Collin county, it's just a form you mail in or submit in person. The typical deadline for filing a Collin County homestead exemption application is between January 1 and April 30. Generally, the deadline to file an application for an exemption is April 30. Military. Military Affidavit. This form is used as proof to the court that a custodial or noncustodial parent is in the military.