If you did not use TurboTax to prepare your 2018 return, it is possible to amend the return using TurboTax but it will really be a pain. It would be better to use the software or service used to file originally.
In order to use TurboTax to amend your 2018 return, you need to purchase the desktop software for 2018 and re-create the return EXACTLY as it appeared when it was filed with the IRS/states. Every line has to be the same. Then you have to "trick" the software into thinking you filed by saying you will mail the return. (but do not mail it) AFTER that, you use the software to prepare a Form 1040X, which has to be printed, signed and mailed to the IRS. It takes the IRS about 3-4 months to process an amended return.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
