Credit card companies often send so-called "convenience checks" to cardholders -- basically checks you can use to borrow against your line of credit for quick cash. Needless to say, you don't want these to end up in the wrong hands. "The worst thing people get in the mail are these convenience checks," Neiser says. "It looks like a credit card bill, but if you open it up, there are checks in there that are live loans ... that to me is very dangerous."
Just because you write "void" on it doesn't mean a canceled check can't be a ticking time bomb. Remember, your account and routing numbers are listed on the bottom of every check. "Not only is the bank account number on there, but there's also your address and possibly your phone number," Neiser says. "And some people write their full credit card number on the check [to pay their bill]." Duplicate checks should have the checking account number omitted for your security. If you have any security concerns but still want proof of payment, Neiser points out that you can usually request a receipt from the recipient (for your property tax payment, for instance), then shred the duplicate check. Canceled credit cards
Sometimes you need to cancel a debit or credit card -- maybe you want to rein in your spending, or you're leaving your bank, or you suspect the number was stolen. So do you need to shred the old one? "Theoretically it's not supposed to be problem, but we recommend that people cut through the magnetic stripe, as there's encoded information on there," Blank says. "Also, you don't want people to know where you bank." If your shredder can't handle plastic, Blank recommends cutting it into four pieces, then throwing the parts into at least two different trash bags. Hey, you can't be too careful. >To submit a news tip, email: email@example.com. Follow TheStreet.com on Twitter and become a fan on Facebook.