text: can a father sue his son? if the dad cosigned for a loan for the son, and the son lost his job and is late on his payments, who is responsible? if the father pays until his son can does the dad have the right to sue him for what he(the dad) has paid? you can sue anyone for anything, whether or not you win is a different story.  but, if you cosign for a loan, you are taking responsibility for the loan if the primary signer doesn't meet their obligations.