Sam had $40 in his account. He bought coffee in the morning for $6. Lunch for $14. A small online order in the afternoon for $25.
Total spent: $45. Five dollars over the balance.
The first two purchases went through. The third one pushed him into overdraft. Then the rent direct debit hit. Then his streaming subscription. Then his phone bill. Each one triggered a $35 overdraft fee.
Five days later, Sam was looking at $105 in overdraft charges. More than the original purchases that started the cascade. He had not checked his balance that morning because he had checked it Friday and there was enough.
Our minds estimate our balance from the last time we looked, not from what is actually there right now. Sam is not bad with money. His brain simply held onto Friday's number, the way all our brains do when checking is friction and the recent memory feels close enough. This behaviour has a name: Availability Bias.
The fix is not more discipline. It is structure. An automated alert from the bank when the balance drops below a set number. A weekly five-second glance at the actual figure, not the remembered one. Cancelling the overdraft protection setting that turns small mistakes into expensive ones.
TL;DR
- Situation: A small purchase pushes your account into overdraft. Other automatic charges hit in the same day. Fees stack up.
- What your mind does: It estimates the balance from the last time you checked, not from what is actually there now (this is called Availability Bias, see below).
- Consequence: A $5 overdraft can trigger $100 or more in fees within days, more than the purchases that caused it.
- What to do: Set up a low-balance alert. Glance at the actual balance once a week. Turn off overdraft protection if your bank allows.
What to do
- Set up a low-balance alert with your bank. Trigger it at a number that gives you 48 hours to react.
- Glance at your actual balance once a week. Five seconds. The number in your head is rarely the number in your account.
- Turn off overdraft "protection" if your bank lets you. Most do. A declined card is cheaper than a $35 fee.
- Move automatic debits (rent, subscriptions, bills) to the day after payday, not before. The order of operations matters.
What not to do
- Do not estimate your balance from memory. Memory is from Friday. Today is Monday.
- Do not assume small purchases are safe because the balance "felt" fine yesterday. Today's balance is the only one that counts.
- Do not pay an overdraft fee without calling the bank and asking for a one-time waiver. Many banks waive the first one if asked.
An overdraft fee is not a penalty for spending too much. It is a penalty for trusting a number you remembered instead of a number you checked.
Want to understand why this happens?
Availability Bias is the brain's habit of using whatever information is easiest to recall as if it were current, accurate and complete.
The balance you saw on Friday is available. The balance right now is not, unless you check. So when Monday morning comes and you tap your card for coffee, the brain reaches for Friday's number, not Monday's. It feels confident. The confidence has nothing to do with whether the number is correct.
Researchers have shown this same effect in dozens of contexts. People estimate the frequency of plane crashes higher right after news of a crash, even though the actual frequency has not changed. They estimate their own driving skill above average because they remember their best driving moments more vividly than the average ones.
It is not you. It is how every human brain estimates anything it has not measured.
The fix for money is to replace memory with infrastructure. An alert, a glance, a habit. Five seconds a week of looking at the actual number breaks the loop. Without it, the brain keeps reaching for Friday.
"We trust what comes to mind easily, even when what is actually there is something else entirely." — Daniel Kahneman (paraphrased from Thinking, Fast and Slow, 2011, chapter on the availability heuristic)
This is called Availability Bias. Daniel Kahneman, Thinking, Fast and Slow (2011).
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