Typically, when a parent opens a joint bank account with a minor, the parent becomes a co-owner and has full access to the account. Depending on the bank's policy, the child who is a co-owner may also have full access to the account, including being able to make withdrawals. Some banks that offer special child accounts may limit children's access, such as requiring their co-owner parent or guardian to sign in with their username and password to approve transfers or withdrawals.