Ok ... let me guess ... you did not file the form 8962 on the original return ... then the IRS required you to send the form 8962 & 1095-A later ... so if this is the situation review your return after you completed the 8962 in the program ... it should confirm you had to pay back $600 of the advance credit ... thus when the IRS finished processing the return with the additional forms they sent you the new correct refund.