I think I know the answer, but not sure. If you are a cosigner on a student loan, can the cosigner claim the interest or can it only be claimed by the student?

A co-signer can claim the interest IF the co-signer actually made the payments---which you say you did not make.  If your son made the payments he can take the deduction for the interest on his own tax return---unless he is still being claimed a dependent or is filing married filing separately--which would disqualify him from using the deduction.

Thank you !!  Appreciate the quick reply.