First:  Check the look and feel

This is as far as most people go, and it’s good enough most of the time. US bank notes are printed on special paper that’s 75% cotton and 25% linen. The linen gives it an extra stiffness that’s distinctive. There are also red and blue fibers imbedded and blended right into the paper.  US currency is printed with a process called “intaglio” that leaves ink on top of the paper, giving the money a distinctive texture. The printing is also very high in quality.  The lines are always sharp and clear, never  broken, fuzzy or blotchy.

Second:  Check for color shifting ink

Color shifting inkBank notes higher than the $5 bill, use color shifting ink to print the number showing the denomination in the lower-right-hand corner.   Just look at the numbers head-on, and then from an angle.  For genuine US currency,  the color will shift (copper-to-green or green-to-black).

Third:  Check for the watermark

Hamilton portrait and watermarkAll bills largerr than a $2 bill, now have a watermark.  When the bill is held up to light you can see an image that matches the portrait of the president.  The new $5 bill released in early 2008 however, have a big numeral 5 for a watermark.  Either way, you can use it to spot bills that have been bleached and reprinted with a higher denomination.

Fourth: Check for the security thread.

Security thread

All bills bigger than a $2 have a security thread running vertically through the bill. Like the watermark, you hold the bill up to the light to see it.  You’ll be able to see the domination of the bill, in tiny print.  The threads also glow different colors under ultraviolet light, but that’s not much help to ordinary folks.)