See this TurboTax support FAQ for amending a 2017 tax return originally completed and filed using the online editions - https://ttlc.intuit.com/community/amending/help/how-do-i-amend-my-turbotax-online-return/01/27371
To access your current or prior year online tax returns sign onto the TurboTax website with the userID you used to create the account - https://myturbotax.intuit.com/
Scroll down to the bottom of the screen and on the section Your tax returns & documents click on Show. Click on the Year and Click on Amend (change) return and Download .tax file
See this TurboTax support FAQ for when access to the online tax returns expire - https://ttlc.intuit.com/community/prior-year-return/help/when-does-access-to-my-prior-year-turbotax-...
The 2019 online editions are available so you can start a 2019 tax return using the Free edition then upgrade and pay for Plus so that you can access the prior year online tax returns - https://turbotax.intuit.com/personal-taxes/online/
- Select Upgrade in the left-hand menu. (If you can't see it, select the menu icon in the upper-left corner, and/or select Take me to my return if you're not in your return yet.).
- In the new window, select PLUS, then select Upgrade Now (if PLUS is grayed-out, skip this step).
- Now you're ready to pay. On the left side, select File.
- Keep going until you reach the Just a few steps left... screen. On this screen, select Start next to Step 1: Review your order and follow the screens to pay with your credit card (don't pay with your refund if you see that option).
- After you've paid, select Tax Home on the left side. This will take you to You're doing great. Keep going!
- Select Show next to Your tax returns documents to expand the prior-year list and then select Download/print return (PDF) for the tax year you want.
