I have a married filing joint.  They state that they only received $750  Letter 6475 $2100 but they never received that amount.  They are under the impression that once they file they will get the remaining amount.  When I enter their numbers and enter the impact letter their return is less than if I file without entering information on letter.  I am so confused. Why is refund amount less if they didn't receive the entire $2100.  Can anyone help answer my question

thanks