My tax return was returned because I needed to sign it, what's the last day to send my tax return back?

[rjs · Accepted solution]

If your tax return was sent back to you, it has not been filed. It's as if you never mailed it. If you did not have an extension, the deadline for filing your 2016 tax return was April 18, 2017, so you are now late. If you are getting a refund, there is no penalty for filing late, and you have until April 15, 2020 to file and get a refund for 2016. If you owe money, you should file as soon as possible because the penalties and interest that you will have to pay will keep increasing until you file.

[fanfare]

"it's as if you never mailed it".
 I don't think that's true, since they only send back the first or second page for signature.

[SweetieJean]

There really isn't a time limit.