How to detect a counterfeit?

How to Spot Fake US Money

Counterfeit currency is more common than you might think, but there are reliable ways to protect yourself. The US dollar includes several security features that make it easier to spot fakes—if you know where to look.

One of the most important features is the security thread, a thin plastic strip embedded in the bill. For a $5 note, this thread runs vertically and displays “USA FIVE” when held up to light. On a $10 bill, it reads “USA TEN.” This thread isn’t printed on the surface—it’s actually woven into the paper, making it hard to replicate accurately.

Another quick test is using a black light. Genuine US bills have special ink that glows under ultraviolet light. The security thread on real money will glow under a black light—green for the $5 bill—while counterfeit notes often don’t react at all, or glow unevenly.

Holding the bill up to a regular light source is also a smart move. Look for a watermark—a faint image of the portrait that appears on the right side of newer bills. On a $20 bill, for example, you’ll see a faint outline of Andrew Jackson. This watermark isn’t printed; it’s created by varying the paper density during manufacturing, which makes it extremely difficult for counterfeiters to duplicate convincingly.

Other details to watch for include color-shifting ink (on bills $10 and higher), raised printing that you can feel with your fingertip, and clear, crisp fine line patterns that blur in fake versions.

In daily transactions, especially with larger bills, taking a few seconds to check these features can save you from accepting counterfeit cash. It’s not about suspicion—it’s about awareness. The more familiar you become with real money, the easier it is to spot what doesn’t belong.