Banks very often play with dates to make you think you have different amounts of money than you really have in an effort to cause you to bounce or overdraft. Say you deposit money through an ATM after the bank is closed, then go use your card to make a purchase. Each transaction has 2 times. The time when the transaction was actually made, and the time it cleared the system. So while your deposit time was in the evening, the clear time is sometime the next business day. The purchase time has the time you made the purchase, we'll say the same evening, and the time the transaction goes through their credit system, sometimes up to a week later.
A common bank trick is to use the clear time as the effective time of deposits but the transaction time as the effective time for purchases. So even if you physically deposit money before you make any purchases, if any transaction happens before the deposit clears, (even if the transaction hasn't cleared) you could get an overdraft even though you never actually spent money you didn't have. This would be akin to a check bouncing because you didn't have the money in the account at the time you put pen to check instead of when the check receiver tries to cash it.
Now one defense of this might be "it's to prevent fraud and people overspending with money they don't have and disappearing". That may be true, but the right thing to do would be to not give you an overdraft if you are indeed an honest customer who in fact did deposit enough money before you made the purchase. But banks don't do that, mainly for the hefty overdraft "processing fee" that is 100% profit for them because of a few twisty fine print rules.
I used to have accounts at National City. They played these games on me exactly as you described. They made me bounce two checks this way, and charged me nearly $200 in fees for it, before I managed to escape their clutches.
Actually, now that I think about it, it was worse than you describe.
NatCity maintains two different account balances for you. One is a balance showing all deposits and debits posted in a timely fashion, within a day or two, the way you'd balance your checkbook. The other balance shows debits posted immediately, but deposits delayed by a week or two. Naturally, this second balance tends to show a lower account balance, due to their delays in posting your deposits.
By timing the way the deposits are posted, they can induce you to overdraw your account. They show you the first balance whenever you query your account online or at an ATM, which shows a higher balance. They figure your overdrafts by using the second, lower balance.
I don't know if it's a common practice at all banks, but it's only been done to me by NatCity. I've used a number of other banks over the years without any of these games.
