How to Use a Marker to Check if Bills Are Real

The ability to identify genuine currency is increasingly important for the general public. The circulation of counterfeit money poses a financial risk to individuals and businesses alike. Having simple, accessible tools for verification can help mitigate this risk and protect against economic losses.

Understanding Counterfeit Detection Markers

A counterfeit detection marker is a tool to distinguish authentic currency from fake bills. These markers contain an iodine-based solution which reacts differently with various paper types. Genuine U.S. currency is printed on a unique blend of 75% cotton and 25% linen fibers, which does not contain starch. Most counterfeit bills, however, are produced on standard wood-based paper that does contain starch. When the iodine solution in the marker comes into contact with starch, it causes a distinct color change.

Using the Marker and Interpreting Results

To use a counterfeit detection marker, make a light stroke on a blank, unprinted area of the bill. For genuine currency, the mark will remain clear or turn a pale yellow or amber color. If the bill is counterfeit, the mark will quickly change to a dark brown or black color. This distinction typically occurs within two to three seconds, providing a rapid assessment.

Other Ways to Identify Counterfeit Currency

While a marker offers a quick check, it is not foolproof. A comprehensive approach involves examining multiple security features in genuine U.S. bills.

One can feel the paper, which has a slightly rough texture. Holding the note to light can reveal a watermark, visible on denominations $5 and higher, and a security thread embedded vertically within the paper. This thread glows a specific color under ultraviolet (UV) light.

Tilting the bill can show color-shifting ink, where the numbers in the lower right corner change color from copper to green on denominations $10 and higher. The $100 note also features a 3-D Security Ribbon woven into the paper, with images that move when the note is tilted. Additionally, genuine currency contains microprinting and small red and blue security fibers embedded throughout the paper.

What to Do with Suspected Counterfeit Bills

If you suspect you have received a counterfeit bill, take specific actions to preserve evidence. Do not return the bill to the person who passed it. Limit handling and place it in a protective covering (e.g., an envelope) to preserve evidence.

Note the circumstances of receipt, including details about the passer, time, and location. Contact your local law enforcement agency or the nearest U.S. Secret Service field office. Provide details about how you received the bill to assist investigations. Knowingly passing on a counterfeit bill is illegal and can result in legal consequences.