It can be hard to tell if a bill is real or fake with a quick glance. Next time you get change, the secret service says it’s worth a second look. The Secret Service says there has been an increase in counterfeit money use, and the 20 dollar bill is the most commonly replicated in the U.S.

"I would encourage you to pick up from top to bottom and look for the security features,” said Timothy Kirk, U.S. Secret Service Resident Agent in Charge.

Official currency has about half a dozen features sewn in. There's a watermark. Look for a replica of the face on the bill hidden on the right. On the other side, there's a vertical blue thread.

“If I lose 20 bucks it might sting a little bit, but I can recoup that,” said Kirk. “If I lose 100, it might hit my pocket book. That's Christmas. Someone gets crossed off the list, potentially."

Last year, more than $100 million in fake money was passed in the US.

"Cashiers in retail stores, individuals should be vigilant when accepting currency as either payment and/or change," said Kirk.

No matter how you get the counterfeit money, the government cannot reimburse you.

"Report it to law enforcement,” said Kirk. “They should segregate the note, not handle it. Put it in an envelope. And get a description of the individual."

Another issue is people using movie money in real life. Instead of seeing United States of America, it would say for motion picture use only or another identifying factor. "Movie money" is easily found online. The secret service has seen a 25 percent increase this year.

It is a felony to use counterfeit money. The penalty is up to 25 years in prison and a fine. You also have to pay restitution to the business you ripped off.