You can't. It sounds like when they applied their estimated income was likely below 200%.  Between 100-200% the credit would be higher,  so at 242%, they would not be eligible for the full credit.  Which means, if they received the full credit amount, they would have to pay it back.  However, the repayment amount should be capped at $975 if they are single and $1,950 for any other status.