It is too late to efile a 2015 return with TurboTax. Efiling for 2015 returns closed in October. A 2015 return can only be printed and mailed at this point.
If you are due a Federal refund, there is no penalty for late filing. However, to claim any refund you have up to 3 years from the original due date or extension due date, if an extension was timely filed.
If you have Federal taxes due, however, then you should file and pay as soon as possible to put a halt to the accruing penalties and interest.
