As a general rule, an employer (or anyone else) cannot make a withdrawal (by reversing a deposit or otherwise) any amounts from a person's personal account without the person first having authorized it. However, you may need to check anything that you have signed with your former employer. Typically, when when an employee signs the authorization for payroll deposits, it almost always authorizes withdrawals under a situation such as yours. That having been said, legally you do owe your empoyer this overpayment and must return it if asked. To keep it would amount to an "unjust enrichment" which the law disfavors.