The online version of TTX can only be used for the current tax filing year, which at this time is 2019. To file a prior year tax return you have to purchase and install the CD version of the program on your windows or MAC computer.
TurboTax only supports their software for the current tax year and 3 years back. Therefore if you need to file a tax return for a tax year prior to 2017 you can not use the TurboTax program. While you may be able to find older versions of the program on places like Amazon, you will not be able to get the *REQUIRED* updates and corrections for the TurboTax program prior to 2017. Therefore chances are high the tax return will be wrong. The TurboTax 100% Accuracy Guarantee does NOT apply to unsupported tax years.
You can get blank forms for prior tax years on the IRS website, fill them out by hand and mail them to the IRS. Or you can seek the services of a tax professional in your local area.
