My clients return was rejected because a dependents SSN was used on a previous filed return (mother of child) for the daycare credit Form 2441.  Both the mother and father each pay half of the daycare expenses ($2,100 each).  Per their child custody agreement, for 2023, the father gets to file as HOH (child living with him for over 6 months) while the mother gets the dependency credit.  Does my client need to paper file to receive the Child Care Credit?  If he paper files, would the IRS give him the $1500 ($300 credit) and recoup from the mother the difference?  Or can he claim the difference from what the mother reported when e-filing or will this also reject because of the use of SSN?