I also had to learn the hard way about how debit cards actually work. At the time, I wasn't doing any online banking, relying solely on an ATM to tell me the balance in my checking account. I was a moron. I had recently made a few pretty big purchases with my debit card, but they had been made 6 or 7 days prior to the day in question.

I went out and bought some stuff, keeping easily within the "balance" remaining in my checking account. A couple days later, two weeks worth of debit charges hit my checking account at once. Apparently, its "okay" and "common" for banks to take up to 14 days to debit your account.

Example:
Today, I have $500 in my bank account. I go out and spend $100, using my debit card. For the next 24 hours, my ATM balance (my online banking rocks, and gives me an actual vs a ledger balance, blah blah, so it tallies this kind of crap, until it actually clears) will read $400.

After that 24 hour period, my bank account will again show $500. Until the debit actually clears the account - up to a week, two weeks later? - I'll think I have $100 more than I do in my account.

I was an irresponsible teenager at the time, and a moron at that, but I ended up with something like 14 debits on a negative account. And at $20/each, they wanted $280. I called and raised holy hell, and they waived almost all of the charges, because it was my "first time."

So, uh, beware.

I've since wised up [img]/images/graemlins/crazy.gif[/img]