Overdraft Is an Engineering Problem

Seventy percent of check cashing customers in the United States have bank accounts. They're not unbanked. They're paying $20 at the check casher because depositing that paycheck at the bank means waiting days for the funds to clear, and every bill that hits the account in the meantime triggers a $35 overdraft fee. Three bills during a hold period and the bank collects $105.

That ratio, $20 for instant access versus $105 for waiting, tells you everything about how overdraft actually works. A price extracted by a system where funds availability, transaction ordering, and batch settlement interact to maximize the number of times a balance dips below zero.

The engineering is the product.

How transaction reordering multiplies fees

Start with $200 in a checking account. Over the course of a day, four transactions hit: a $5 coffee, a $15 lunch, a $60 gas fill-up, and a $180 student loan auto-payment.

If the bank processes those transactions in the order they occurred, the first three clear fine. The student loan pushes the balance negative. One overdraft. One $35 fee.

Banks are legally permitted to reorder debits from largest to smallest before posting. The $180 student loan posts first, leaving $20. The $60 gas purchase overdrafts. Then the $15 lunch. Then the $5 coffee.

Four overdrafts. Four fees. $140 instead of $35, on the same transactions, from the same starting balance.

The coffee didn't cost $5. It cost $40.

The banks that run on overdraft

Bank of America averages about $2 in overdraft revenue per customer. Woodforest National Bank, which branches inside Walmart stores, averages $95.

Woodforest generates roughly two-thirds the gross overdraft revenue of Bank of America with a fraction of the customer base. It targets consumers who can't open accounts elsewhere because they appear on ChexSystems, a database that tracks people whose previous accounts were closed involuntarily. Woodforest offers them "second chance" checking.

The business model is straightforward. Find customers who overdraft frequently, give them accounts other banks won't, reorder their transactions, and collect the fees. Over a ten-year period, Woodforest's overdraft revenue exceeded its total net profit from all other banking activities combined.

It is a check casher with a national bank charter.

The pattern repeats. Eight percent of account holders generate 80% of all overdraft revenue in the United States. These aren't people who occasionally miscalculate. They're people whose income arrives on a schedule that doesn't align with when their bills post, living in a system that charges them for the mismatch.

Funds availability is the mechanism

The reason check cashers can undercut banks on a product that banks invented comes down to one thing: speed.

When a paycheck is deposited on a Friday, the bank may not make those funds available until the following Tuesday or Wednesday. If the weekend includes a federal holiday, add another day. The Federal Reserve closes its payment systems on holidays, and ACH settles in batch cycles that depend on when the transaction entered the queue and where in the country it originated.

During the gap between deposit and availability, any debit that hits the account can trigger an overdraft. Direct deposit doesn't solve this.

ACH is a multi-day process regardless of whether the deposit is a paper check or an electronic payroll file. The money was probably pulled from the employer days before it shows up in the employee's account.

The check casher charges a flat fee, typically 1% to 3% of the check amount, and hands over cash immediately. The bank holds the same check for days and charges $35 every time a debit posts against a balance that would have been positive if the funds had arrived on time.

Banks that have shortened their funds availability windows have seen overdraft revenue decline by as much as 50%. The fee isn't a consequence of consumer behavior. It's a consequence of when the system decides your money has arrived.

The law says faster. The Fed says no.

The Expedited Funds Availability Act, passed in 1987, requires the Federal Reserve to make funds available "as fast as technology allows." Since 1987, the Fed has changed the hold time zero times.

The law uses the word "shall," which in legislative drafting means the agency has no discretion. The Fed has treated it as optional. Aaron Klein of the Brookings Institution submitted a formal petition to the Fed in 2024, as any citizen is entitled to under the Administrative Procedure Act. The CFPB, which shares some jurisdiction, responded in writing and agreed with the petition. The Fed has not responded.

Real-time payment rails exist. The Clearing House launched RTP in 2017. The Fed launched FedNow in 2023. Over 1,800 of roughly 8,500 US banks and credit unions have joined FedNow as of mid-2026, and most are receive-only, meaning they can accept an instant payment but cannot send one.

FedNow was designed without a mechanism for consumers to request instant settlement. Senator John Fetterman asked the Fed how much banks charge their customers to use FedNow. The Fed said it doesn't know. Fetterman asked why they don't find out. The Fed said it doesn't want to know.

The math that keeps the system in place

Overdraft revenue in the US runs into the tens of billions of dollars annually. For many small and mid-sized banks, and for credit unions, it represents 20% to 30% of net profit. Eliminating overdraft by moving to real-time settlement would cut that revenue line in half or more.

The institutions that regulate banks also depend on bank profitability for the system's stability. The incentive to preserve overdraft revenue is structural, not conspiratorial. Nobody needs to be corrupt for the outcome to persist. The regulators just need to keep not acting, which is exactly what has happened for 38 years.

The engineering that produces overdraft, batch settlement, transaction reordering, and multi-day holds, is the revenue model. And the revenue model is why modernization keeps not arriving.