An overdraft happens when a payment takes your checking account below zero. If your bank covers the payment anyway, it charges an overdraft fee for the favor — commonly around $35, per transaction. Three small purchases while you are negative can mean three fees. It is one of the most expensive ways to borrow $20 that exists.
The plumbing is simple. A charge arrives — a debit card purchase, an automatic bill, a check. Your account does not have enough in it. The bank then chooses: refuse the payment, or cover it and let your balance go negative. If you are signed up for debit card overdraft coverage, it covers — and the fee clock starts.
The stacking problem
The fee is not once per bad day. It is once per transaction the bank covers while you are short. A low balance in the morning can meet the electric bill, a grocery run, and a gas purchase by evening — three covered payments, three fees, before you have seen a single alert. Some banks also add an extra fee if the account stays negative for several days running.
Your balance is $40. A $25 gas purchase, a $30 grocery run, and a $12 lunch all post while your rent check has quietly cleared first, leaving you short. If the bank covers all three small purchases at $35 a fee, that is $105 in fees on $67 of spending — the bank earned more from the day than the stores did. Numbers vary by bank, but the shape of the trap does not.
Your real choices
You can opt out of debit overdraft coverage entirely: then a purchase your account cannot cover is simply declined — embarrassing at the register, but free. Many banks offer overdraft protection instead, which pulls the shortfall from your savings or a small credit line for a much lower charge or none. And a growing number of banks have dropped overdraft fees altogether — worth knowing when you next shop for an account.