If there is no joint signer or “pay at death” beneficiary, the funds go into her estate. However, banks today do not open accounts without the account holder naming a beneficiary at death, and elderly people often want a co-signer on their checking accounts to help pay bills. For this reason, checking accounts are often not probated by courts, but rather, are distributed outside by the will. If your mother’s household checking account has your brother as a co-owner, he becomes owner of all those funds at your mother’s death, even if he contributed nothing to the account.