Is the difference actually over the filing requirements for the kid?

no, problem is on student's return he has $12,000 part-time w-2 and when putting 1098-T on his return, he has to pay $400 taxes. mother return no taxes due.

1098-T forms are notoriously incorrect.  I would get a financial transcript from the school. 

Are you sure Mom is not a dependent of the son, who can file Head of Household?

I agree, I'm trying to get a transcript from school.  I know that room and board was taken out of schlorships and grant, but now listed on 1098-T.  Thanks

Thanks, I'm working on getting the difference down.