There is only one file type that uses the .TAX2012 extension:
TurboTax 2012 Tax Return
Tax return created with TurboTax 2012, a United States tax preparation program; contains federal and often state tax forms, along with user data entered through TurboTax; stores your progress when completing a tax return and allows you to pause and resume your tax return at a later time.
A TAX2012 file contains data specific to the 2012 tax year. Since 2012 taxes are filed in 2013, TAX2012 files are usually created in 2013, rather than 2012. Once you complete a tax return in TurboTax, you can either file it directly from the program via e-file or you may print and mail the tax forms, which Turbo Tax automatically fills in.
TAX2012 files may also be exported from TurboTax Online. To create a TAX2012 file with TurboTax Online, click the "Save your 2012 return to your computer" link in the lower-left corner of the browser window, then click "Save." You can then name the file and save it to your local disk. Files exported from TurboTax Online can be opened and edited in TurboTax 2012.
NOTE: Since TAX2012 files contain personal financial data, you can select "Encrypt and password protect this document" when saving your tax return. Once your tax return has been secured with a password, you must enter the correct password in order to open the file.
Tax Return 12.2012 - The default filename used for saving a new tax return document.
Updated: August 24, 2016