Debit cards help you avoid overdraft charges because your account balances are checked each time you use the card. If you don’t have sufficient funds in your account, the transaction will not be processed. Be aware that the system is not fool proof. The account balances referenced are as of 4:00 p.m. the prior business day and are not updated until 4:00 p.m. the current business day. It is possible to have multiple ATM and debit card transactions that in total overdraft your checking account when posted.