what is overdraft protection 
overdraft protection is an optional service that prevents the rejection of charges to a bank account primarily checks atm transactions debit card charges that are in excess of the available funds in the account overdraft protection sometimes called cash reserve checking is used most frequently as a cushion for checking accounts but it also can be applied to savings accounts with overdraft protection even if the account has insufficient funds the bank will cover the shortfall so that the transaction goes through when a customer signs up for overdraft protection they designate a backup account for the bank to use as the source to cover any overdrafts usually a linked savings account credit card or line of credit however the bank charges the customer for this service in a few ways e g overdraft fees to process any transactions that overdraw the account 