If you have NOT e-filed yet you can edit/change/fix your 2020 return as needed. If you did e-file, you cannot fix anything now.
Did you e-file? Did you click that big orange button that said “Transmit my returns now?” If so, your return is now in “pending” on a server. Do not try to change anything while your return is in pending.
First your e-file is going to sit on the server until the end of January when the IRS begins to accept/reject 2020 returns. anything while your return is. Watch your emails so you will know by then if your return is accepted or rejected.