Overdraft protection is a financial service offered by banking institutions primarily in the United States. Overdraft or courtesy pay program protection pays items presented to a customer's account when sufficient funds are not present to cover the amount of the withdrawal. Overdraft protection can cover ATM withdrawals, purchases made with a debit card, electronic transfers, and checks. In the case of non-preauthorized items such as cheques , or ACH withdrawals, overdraft protection allows for these items to be paid as opposed to being returned unpaid, or "bouncing". However, ATM withdrawals and purchases made with a debit or check card are considered preauthorized and must be paid by the bank when presented, even if this causes an overdraft.