After you file

I thought that you wouldn’t get the refund if you forgot to include 1095A.  Other answer is that the IRS will send you a letter you fax the 1095A and correct it on your return than once IRS gets it, it takes 3,weeks or more to get refund???  I forgot to include my 1095A my return has been accepted ...Does anyone know the correct answer? When do I amend? Thanks!