If someone you don’t know wants to pay you by check and wants you to send some of the money back, beware! It’s a scam that could cost you thousands of dollars.

There are many variations of the scam. It starts with someone offering to buy something you advertised for sale, pay you to work at home, give you an "advance" on a sweepstakes you won, or pay the first installment on millions you’ll receive for transferring money in a foreign country to your credit union account for safekeeping. The scammers often claim to be in other countries and say it’s too difficult to pay you directly, so they’ll have someone in the U.S. who owes them money send you a check.

The amount of the check may be more than you’re owed, so you’re instructed to deposit it and wire the rest to the scammer. Or you’re told to wire some of the money back to pay a fee to claim your "winnings." Whatever the set-up, the result is the same – after you wire the money, the check bounces.

These checks look so real that even tellers may be fooled. Under federal law, financial institutions must make the funds you deposit available quickly – usually within a few days. But just because you can withdraw the money doesn’t mean the check is good, even if it’s a cashier’s check. Forgeries can take weeks to discover.

The credit union works very hard to identify fraudulent checks before they are accepted, but ultimately you’re responsible for checks you deposit, If they bounce, you owe the money that was withdrawn. Financial Institutions may even take it from your account or sue you to recover it. In some cases, authorities could bring charges against victims because it may look like they were involved in the scam and knew the check was counterfeit.

There is no legitimate reason for someone who is giving you money to ask you to also send money back. If you think someone is trying to pull a fake check scam, don’t deposit it – report it!