If you have already e-filed, you will need to wait until your return is accepted or rejected by IRS / the state.
-If your return is rejected, add your new information (along with anything else that needs to be corrected) and then re-submit your return. See Fix a reject
-If your return has been accepted- you cannot change the information. Instead, you have to amend a return. See instructions below.
IRS does not allow e-file for amendment, you will need to submit the amendment forms with related supporting documents by mail. (Follow instructions through the step-by-step interview questions in the program)
If your original return generates a refund, you should wait until your original refund arrives before you file your amendment. You can cash your check, but you still should wait until your current tax return is resolved. Note that if you see " Do Not File" watermark on your Form, this means your original return is either still pending or forms are not finalized yet.
As you are going through the amendment process,
1. On screen, Do you need to change anything else?
2. Scroll down to Deductions and Credits, select Edit
3. Next screen, select Mortgage Interest, Refinancing, and Insurance, select Edit to enter your information