Run your index finger through the bill. Feel the raised ink in certain areas such as the “20″ or “100″. Those numbers should never be solid but rather spattered. Another feature is that they should change colors when shifted to different angles.
Raise the bill up to see through the “ghost image” of the president.
Check to see if it has the “vertical strip” embedded inside the bill.
Compare it with another bill that you know is genuine.
Inspect the print quality. Real money has very sharp images.
Look for tiny red and blue colored strands being randomly imbedded on the paper. Those should not look as if they’re printed on, but rather pressed on.
Put the bill into “black light.” Authentic dollars will glow: $100 will be red, $50 will be yellow, $20 will be green, $10 will be orange, $5 will be blue, $1 … haven’t tested that.
Lay the bill flat on a table, and run your finger nails from one end to the other. Real US currency will feel as if it has “ridges”.
Use a 5X to 20X magnifying glass to check for “micro-printing.” $100 bills will say “United States of America” as a circle around President Benjamin. $20 bills will say “twenty bucks,” or something to that effect.
The new dollar bills will have Federal Reserve indicators and unique eleven-digit serials that act as codes to check against the printed money database. Cops and Banks can enter these numbers into a computer to go ‘voila’ if the bill is ‘funny.’