After you file

You cannot have amended a 2019 return, since the necessary Form 1040X is not yet available.  What did you do?

The 1040X becomes available late in February, so you have to wait for it.  If your return is still being processed now, it would not be a good idea to amend yet anyhow.  Sending in an amended return while they are still processing your original return could cause confusion that would delay your refund for months.

Check back later for the 1040X.   AFTER your return has been fully processed.

How do I amend my 2019 TurboTax Online return?

The only way to file an amended tax return is to prepare a 1040X and print, sign. and mail it.  If you did something else, like try to e-file a change, the changes were NOT TRANSMITTED.

You can amend a tax return after it has been fully processed and you have received your refund.  You must work from your return exactly as it was when you first filed it. If you changed anything, change it back to the way it was when you originally filed it, before you follow the steps to amend. Follow the TT instructions to amend a tax return:

https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed?...

Wait about 3 weeks and you can check the status of your amended return:

https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1

It will take about 3-4 months for the IRS to process an amended return.

https://www.irs.gov/filing/individuals/amended-returns-form-1040-x/amended-return-frequently-asked-q...