I filled out the 4868 extension with TurboTax, it said it was Complete. Did you file it? I got no message from TT and wonder if I must print+mail it.

If you e-filed Form 4868 with TurboTax, you do not need to print and mail it. However, if you owe federal taxes, include your estimated payment with your Form 4868 and mail it—postmarked by April 18, 2017 to avoid any penalties or interest. Then complete and file your return on or before October 17, 2017.

I don't owe IRS, the problem was knowing whether the desktop TurboTax extension "Complete" message meant the 4868 was actually e-filed by Turbo Tax, or if it meant the form was created and saved, but not filed.  TurboTax screens imply an extension *must* be printed & mailed.  I had no printer available ...

After getting the ambiguous "Complete" message, I gave up on the desktop client and tried turbotax.com, which clearly declared "Sccess - your extension was sent to IRS".  Not sure why desktop message is so vague.

TurboTax called late last night to confirm that "Complete" means "form created and sent".  I asked them to provide better messages, consistent with website.