You can select to e-file your 2016 return in Step 3 of the File section of TurboTax. Keep in mind, that some returns simply can't be e-filed due to IRS regulations.

1. Sign in to TurboTax and continue your tax return by clicking the orange Take me to my return button.
   - If you originally selected to File by Mail, click Add a State to get back into your return and change your filing method
2. Click the File tab
3. Click Start next to Step 3
4. Choose I want to e-file and complete the File section
5. Click Transmit my Return to complete the e-file process

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