What is an overdraft fee, and why is it so expensive?
Being three dollars short and being three hundred dollars short cost exactly the same, which tells you it is not really a fee for the money.
Each item that clears while the balance is negative stacks its own flat fee, regardless of size.
The arithmetic that makes it remarkable
A flat fee on a large shortfall is unpleasant. A flat fee on a tiny one is something else entirely.
Cover a shortfall of a few dollars for a few days, charge a flat fee many times that amount, and the annualised cost runs into the thousands of percent. Nobody quotes it that way, because it is not structured as a loan. Structurally it is one: money advanced, repaid, at a price.
This is exactly the case where APR as a comparison tool falls apart, and it falls apart in the direction that flatters the product.
Ordering, and why it used to matter so much
For years the fees were multiplied by a practice that was entirely invisible: the order transactions were processed in.
Process the largest transaction first and a balance can go negative early, so every smaller purchase afterwards also triggers a fee. Process smallest first and often only one does. Same transactions, same day, several times the fees.
Litigation and regulation have curtailed the worst of this, but ordering rules still vary, and it remains the clearest illustration of how a fee can be engineered by something the customer will never see.
Three things people confuse
Overdraft fee. The bank covered it and charged you.
Non-sufficient funds fee. The bank declined it and charged you anyway. You paid for a payment that did not happen.
Overdraft protection. A linked account or line of credit that funds the gap, usually far cheaper. Almost always worth having and frequently not switched on.
What changed
This became one of the most scrutinised fees in retail banking. Several large banks removed or sharply cut them, some eliminated NSF fees entirely, and challengers made "no overdraft fees" a headline feature precisely because it was such an effective wedge.
The reason it drew that scrutiny is concentration. A minority of customers generate most of the revenue, and they are systematically the customers with the least buffer. A fee that lands hardest on people closest to zero is difficult to defend for long once it is measured.
A shop that spots you when you are short, and charges the same recovery fee whether you were short by a coin or by a week's wages. The fee is not for the money. It is for the moment.
Where you meet it
Every account that went negative by an amount smaller than the fee, every subscription that renewed on the wrong day, and every "no fees" advert that is aiming squarely at this.