I feel like I'm a relatively sophisticated user of banks and financial institutions, but My Mint just proved me wrong, offering insights into three banking laws that directly affect every finance customer, especially those of us who do substantial business online. If you've even got a single ATM card in your wallet, you should definitely read on.

Here are the three rules:

• Regulation D - I had no idea, but Reg D limits you to three outgoing electronic funds transfers each month on savings or money market accounts. Online, wire transfers, phone transfers all count, as do (surprisingly) checks written directly against these accounts. If you want a 7th transaction, you'll have to do it in person or via ATM or a written request in the mail. Go past the limit and your account could be suspended or closed.
  
• Check 21 - This says that banks no longer need to keep hard copies of checks you write. If you want a copy it will come in digital form instead. This also means checks clear faster than before since they aren't physically mailed around the country by the banks. (Watch those overdrafts!) There are also rules about how to deal with double-payment of checks.
• EFT Act - This rule deals with mistakes and loss regarding your ATM card. There are extensive rules about how banks must deal with errors, but also limits (or no limit) to what happens if you lose your card. Recently I lost $700 when I left my ATM card in a machine (yes, laugh all you want, I was stupid). Had I discovered the loss within two days I would have been liable for only $50. Within 60 days, my liability would be $500. After that: Unlimited. (Even though I didn't realize I'd lost the card until a week after it happened, Bank of America graciously refunded the entire amount to my account anyway.)
  

The link below has far more information on these three rules than I've digested here. Definitely give them a quick read and keep these rules in the back of your mind when using your debit card or going over your bank statement each month.

LINK: The Three Banking Rules You Should Know (just a little bit more about)