If you filed a return with missing documents and it has already been accepted by the IRS, you will need to wait until the return has been processed and then file an amendment by mail.
If you need to submit an amended return, you will need to wait until the the first return has been processed. The forms will be available in mid-February along with specific instructions. Please see the information below to learn more.
https://ttlc.intuit.com/replies/3288565
