There is only one file type that uses the .TA6 extension:
TaxAct 2016 Tax Return File
A TA6 file is a 2016 tax return created with the 2016 version of TaxAct, a tax-preparation program. It contains tax data for the 2016 tax year, which includes both federal IRS tax forms and state forms for a specific state. TA6 files also store the user's basic information such as name, date of birth, occupation, marital status, dependents, and social security number.
Updated: August 25, 2017