TurboTax Online for 2018 is now closed. You can't e-file a prior-year return. You must purchase and download the Desktop (CD/Download) version of TurboTax, prepare and sign your return, then mail it in. The TurboTax FAQ I'm linking below explains:
How do I prepare a prior-year tax return?
Here's a link to the TurboTax webpage where you can purchase 2018 software.
https://turbotax.intuit.com/personal-taxes/past-years-products/
I'm not sure what you're referring to when you say you already paid TurboTax to prepare your 2018 return. When did you do that? Please clarify and I'll see if I can help.
*** I am NOT a tax expert. I am a seasoned TurboTax user, and volunteer to provide assistance to TT users. Nothing I post is to be considered TAX ADVICE; I bear no legal liability for responses.***
