Dad has individual checking account with bank. Dad has a debit card in his name to access funds.

Dad opens new checking account, joint with son. Son is over age of maturity.

Dad funds new joint account with individual account. Dad orders new debit card for son.

Are you with me so far?

Dad now, for some reason, is using son's debit card for purchases.

With the exception of knowing that Dad can't access joint funds via his own card (which is tied to his individual account), I don't know that Dad is necessarily doing something "wrong"; he is in fact a joint owner on the account, but I can't think of any reason why he should be using the son's card.

Suspicious? File a SAR? Close the son's card? I'm at a loss.

I would recommend a call to the dad to inquire if he would like a card issued in his name? This might help shine some light on the situation.

I think a call to the dad is warranted as well.

Dad may be trying to hide money/expenses from a soon to be ex-spouse.

OP here; thanks all for the suggestions. I'll give Dad a call and see what the exact situation is. The account is funded minimally, so I don't think it's a case of trying to hide any thing. And none of the transactions seem suspicious; Wal-Mart, fast food, etc.

This might be a dumb question, but how do you know that Dad is using the card and not the Son? Maybe Dad is giving an allowance to the Son and the son goes to Walmart & McDonalds, etc. Or, perhaps Dad doesn't realize you can get two debit cards on the same account. I would be more worried about Elder Abuse.