The direct deposit will have both names on it. Some banks will accept it in an account in only one name, and some banks won't. Some banks don't even check the name. They are not required to, but the IRS encourages them to check. You can ask the bank, but the people at the branch or on the phone might not know the technical details of how direct deposits are processed.
If you get a check instead of direct deposit, the check will be payable to both of you (John AND Mary, not OR).
