We have protective payee accounts where a company handles the finances for people unable to do so. The owner of the account does not have signature rights, only the company handling the account has signature rights.

If the owner of the account comes in to cash a check that was made payable to them, should we cash it? They don't have signature rights on the account, so if the check would come back, could we charge it against the account?

If the check was signed by an authorized signer on the account, you should be fine to cash the check. Many of these individuals are given responsibilities for small amounts of money by their rep to help them learn how to manage their finances. If they are bringing in a check from a third party, I would decline. I don't think you could charge that back to the account.