A newly graduated student applied for the RRC on 2021 Return filing as Single nondependent of parents. Received Notice disallowing the $1400.00 RRC claiming error on the Form 1040 listing that one of the five errors was the reasoning. I looked over the errors and cannot agree with any of the reasons they claimed. 

1. It looks like the Student could have been claimed on the parents return because I found out that the student graduated in May of 2021 and not the prior year 2020. Now how would IRS have known this I do not know if this was the reason?

2. Let say I have the student pay on the notice without amending the student's return and have parents amend their return to claim the student? Will they disallow the E-filing because the student's Social Security Number was used on another's Primary Return?