How to spot a counterfeit 100?

How to Spot a Counterfeit $100 Bill

With counterfeiters becoming increasingly sophisticated, knowing how to identify a fake $100 bill is more important than ever—especially in high-cash transactions.

One of the most reliable ways to verify authenticity is by checking the security thread. Tilt the bill toward the light, and look to the left of Benjamin Franklin’s portrait. You’ll see a vertical strip embedded in the paper, not printed on top. This thread is more than just a design element—it’s a powerful anti-counterfeit feature.

The thread is embedded with tiny inscriptions that alternate between “USA” and “100.” You can read these from both sides of the note, even without magnification. More tellingly, when exposed to ultraviolet (UV) light, the thread glows a distinct pink color. This is nearly impossible to replicate accurately with standard printing methods, making it a key identifier.

Don’t rely on texture alone or the watermark—though those help. The security thread is a definitive test. If the thread appears glued on, lacks the inscriptions, or doesn’t glow pink under UV light, the bill is likely counterfeit.

Since the redesigned $100 bill launched in 2013, these security features have made it one of the hardest U.S. notes to fake. But counterfeiters still try. Staying alert and using simple checks—like the security thread—can save you from accepting a fake.

Next time you’re handed a hundred, take a second. Hold it to the light. Look closely. That quick glance could protect you from a costly mistake.