Hold the bill up to the light
You may have seen people do this in movies and wondered what they were looking for. The answer is, security threads. Have you ever noticed those translucent looking plastic strips that run through the width of most dollar bills? These are called security threads. When you hold up US dollars, to the light, the security threads should appear to be a part of the note, as opposed to being printed on it.
Tiny colored fibers
All dollar notes have tiny red and blue fibers embedded in them which should be visible to the eye. These fibers are an actual part of the currency and should not appear as though they are printed on the paper. Often, currency forgers will attempt to mimic this feature by attempting to print these fibers, and if you notice this, it’s a big red flag.
As with most imitations, even the slightest error is an indication that you are holding fake US currency in your hands. There should be no blurred lines or smudges whatsoever, on any part of the note. Also, you can use a magnifying glass to check if the words: “The United States of America" are repeated along the rim of the portrait engrossed on the bill. Every denomination of US dollars will have this feature, but it is not immediately visible to the naked eye, appearing instead as an unbroken line, and is particularly hard to fake.
All US dollar bills and notes should have two matching serial numbers on either side of the note. Obviously, these serial numbers must match otherwise the note is fake. You should also watch out for irregular spacing and other such errors in the printing of the serial numbers.
If you’ve been paid with more than one suspicious looking bill, you should check to see if the serial numbers are the same on more than one of these notes, as counterfeiters will often make mistakes with these details. If more than any note has the same serial number as another, you need to get in touch with the police immediately.
These are a few of the fool proof tips you can use to immediately tell if you’ve been given a fake note or not. So if you’re ever in doubt, simply refer to this list and you should be fine. Note that although you are more likely to find counterfeit US dollars overseas, you may still come across them at home, in the US, and you should always be vigilant.