Can I still e-file a 2013, 2012, or earlier tax return?
Not if you're filing a personal (individual) return.
For these returns, the e-filing "season" goes from January to mid-October after the tax year ends. This is determined by the IRS.
For example, the 2013 tax year ended on December 31, 2013, so that means personal returns could be e-filed anytime from January through mid-October of 2014.
You can still paper-file 2011-2013 and earlier returns using TurboTax. Simply purchase the software and install it on your computer. TurboTax Online is not available for prior-year tax returns.
Only 2013 corporate and partnership returns can be e-filed. Other prior-year business entities' tax returns must be paper-filed.