There are two distinct security features on the $5, $10, $20 and $50 bills the public can use to check the authenticity of their bills. Hold the bill up to the light and check for:
Watermark
Each redesigned bill includes a watermark, which is a faint image within the paper itself. There are now two watermarks on the redesigned $5 bill. A large number "5" watermark is located to the right of the portrait, replacing the watermark portrait of President Lincoln found on older design $5 bill. Its location is highlighted by a blank window incorporated into the background design. A second watermark - a column of three smaller "5"s -- has been added to the new $5 bill design and is positioned to the left of the portrait. The watermarks for the $10, $20 and $50 bills are images of portraits located to the right of the larger portrait found on each denomination. On the $20 bill, the watermark is similar to the large portrait of President Jackson; on the $50 bill, there is a watermark portrait of President Grant; and on the $10 bill, there is a watermark portrait of Treasury Secretary Hamilton.
Security Thread
Each redesigned bill includes an embedded security thread in the paper, which is a plastic strip that runs vertically through each bill. If you look closely, you can see the letters "USA" followed by the number "5" printed in an alternating pattern along the thread on the new $5 bill, "USA TEN" printed on the $10 bill thread, "USA TWENTY" on the $20 bill thread, and "USA 50" on the $50 bill thread. The security thread is visible from both sides of the bill.
Color Shifting Ink
The higher-denomination $10, $20 and $50 bills have a third easy-to-check security feature:
Color-shifting ink: Look at the number in the lower right-hand corner on the front of the new $10, $20 and $50 bills, depicting each bill's denomination. The color-shifting ink changes from copper to green when you tilt the bill up and down.
