I filed an extension in 2018 (for 2017) but never finished my return. How do I access that return to complete it and submit to IRS?

[CarolynM]

If you used the TurboTax desktop program for your Mac, the return is saved on your computer.

You will need to print and mail to the IRS.

[pfielder785]

I did not use the desktop program

[CarolynM]

If you worked the online program, you will need to transfer to desktop program to complete. Here are the instructions:
Here is how to transfer from TurboTax Online to TurboTax Desktop:
1.       Save your online return as a tax data file.
2.       Sign out of TurboTax Online.
3.       Install your 2017 TurboTax software.
o   If you have not purchased TurboTax Desktop software, click here to select the product you need to complete your return.
o   Important: If your return includes a state, make sure you also install the corresponding state program(s), otherwise you'll get Error 539.
4.       Once installed, choose File > Open Tax Return in the software program.
5.       Browse to where you saved your .tax2017 file and click Open.
6.       If you get an error, delete your tax data file and repeat these steps from the beginning.
7.       (Optional) Once you've confirmed that your online return opens properly in the software, you can clear your online return.