When launching a paycard program, you will have to decide how your employer will structure the bank account(s) for the program. Some employers may choose to have their employees' debit cards set up so there is a one-employee-to-one-account relationship. Others may opt for an aggregate or master bank account with sub-accounts established for each employee that are systemically accounted for individually, even though wages of all employees are essentially commingled. You should consult with your payroll card program provider on the options that they have available.
From an employer's perspective, the use of an aggregate/master account for a paycard program will likely cut down on administrative costs as all wages paid to employees using the cards will be sent via one ACH transaction as opposed to multiple transactions with a potential transactional fee associated to each account for each pay period.