To tell if a US bill is counterfeit, hold it up to a light and look for two things inside the paper: a thin security thread that spells out the denomination, and a faint watermark portrait or numeral in the blank space beside the portrait. On a $10, $20, $50 or $100, then tilt the note and watch the numeral in the lower right corner shift from copper to green, and run a fingernail across the portrait to feel the raised ink. A note that passes all of these for its design is almost certainly genuine and worth its face value. A counterfeit is worth nothing as of late 2026: no bank will exchange it, nobody reimburses you for it, and passing it on knowingly is a federal crime.
The checks only work if you compare the note with the right design. Older notes from before series 1990 were made without a thread or watermark and are still genuine, and the $1 and $2 have never had them. The counterfeit pen, which most shops rely on, misses one of the most common modern fakes entirely.
Quick answer
- Hold the note to light: a genuine $5, $10, $20, $50 or $100 from the 1990s onward shows an embedded thread, and from the late 1990s a watermark, both visible from either side.
- Tilt it: on the current $10, $20, $50 and $100 the corner numeral shifts copper to green. The $5 has no color-shifting ink.
- Check that the watermark and thread match the denomination. A "$100" showing a Lincoln or a 5 is a bleached $5.
- Counterfeit pens react to starch in ordinary paper. They pass bleached genuine notes and are not a reliable test.
- A suspected fake goes to the police or the Secret Service, not back into circulation.
How to check a bill, step by step
- Identify the design. Read the series year printed near the portrait. A small, framed portrait means a note from before the late 1990s. A large, off-center portrait on plain paper with no background color means the designs first issued from 1996 to 2000. Pale background colors (peach on the $20, orange on the $10, blue and red on the $50, the blue ribbon on the $100) mean the current designs. You check a note against its own design, not against the newest one.
- Feel the paper. Genuine notes are printed on a cotton and linen paper that feels crisp and slightly rough, not slick or waxy like printer paper. Red and blue fibers are embedded in it; on a fake they are often printed on the surface and cannot be lifted or seen at a slight angle.
- Feel the raised printing. Run a fingernail down the portrait's coat or Franklin's shoulder. Intaglio printing leaves ink you can feel. A flat, smooth portrait is a strong warning sign.
- Hold it to a light for the thread. The thread is a thin vertical strip embedded in the paper, not printed on it. It carries tiny text such as "USA TWENTY" and is visible from both sides. Its position differs by denomination; see the table below.
- Look for the watermark. In the blank space to the right of the portrait, a faint image appears when the note is held to light. It should be the same person as the portrait (Hamilton, Jackson, Grant or Franklin) or, on the current $5, a large numeral 5.
- Tilt for the color shift. On the current $10, $20, $50 and $100, the large numeral in the lower right corner shifts from copper to green. On the $100, the bell inside the copper inkwell does the same. The large-portrait designs first issued from 1996 to 2000 shift from green to black.
- Check the $100's blue ribbon. On the current $100, a blue ribbon is woven into the paper, not printed on it. Tilt the note and the bells on the ribbon change to 100s, and they move side to side when you tilt it up and down.
- Use a magnifier on the microprinting. Tiny text such as "USA 20" or "THE UNITED STATES OF AMERICA" should be sharp and readable. On fakes it blurs into a line or dots.
- Compare with a known genuine note of the same denomination and design. Side by side, color, sharpness and feel differences become obvious.
What each bill should show
Positions are as you look at the front of the note. UV colors are what the security thread glows under an ultraviolet light, a check many shops can do in seconds.
| Note and design | Security thread | Watermark | Color-shifting ink |
|---|---|---|---|
| $1 and $2, any series | None | None | None |
| $5, 2008 design to date | Right of portrait, "USA" and 5, glows blue | Large 5 right of portrait; three small 5s to the left | None |
| $10, 2006 design to date | Right of portrait, "USA TEN", glows orange | Hamilton, right of portrait | Lower right 10, copper to green |
| $20, 2003 design to date | Left of portrait, "USA TWENTY", glows green | Jackson, right of portrait | Lower right 20, copper to green |
| $50, 2004 design to date | Right of portrait, "USA 50", glows yellow | Grant, right of portrait | Lower right 50, copper to green |
| $100, 2013 design to date | Left of portrait, "USA" and 100, glows pink | Franklin, right of portrait | 100 and bell in inkwell, copper to green; blue 3-D ribbon |
| $100, 1996 design (to 2013) | Left of portrait, "USA" and 100, glows pink | Franklin, right of portrait | Lower right 100, green to black |
| Large-portrait $5 to $50, 1990s to mid-2000s | Present, varies by note | Matching portrait | $10 to $50 green to black; $5 none |
| Small-portrait notes, series 1990 to 1995 | Present on $5 and up (some later than others) | None | None |
| Notes before series 1990 | None | None | None |
The last two rows matter. A 1985 $20 with no thread and no watermark is a genuine note, legal tender at face value, and occasionally worth more to a collector; see our guide to the old 20 dollar bill. Judge it on paper, raised printing, fine line detail and the red and blue fibers instead.
What a genuine note and a fake each show
| Check | Genuine note | Typical counterfeit |
|---|---|---|
| Paper | Crisp, slightly rough cotton and linen | Smooth, glossy or limp; feels like printer paper |
| Red and blue fibers | Embedded in the paper | Printed on the surface, or missing |
| Raised ink | Felt on the portrait and large lettering | Flat everywhere |
| Fine lines around portrait | Sharp, continuous | Broken, blurred or merging |
| Thread | Inside the paper, readable both sides, glows the right color | Drawn on, missing, wrong text, wrong glow |
| Watermark | Soft, shaded, same person as portrait | Missing, printed on the surface, or wrong person |
| Color shift | Clear change when tilted | Metallic or glittery ink that does not change |
| Microprinting | Readable under 5x | Blurred into lines |
| Pen mark | Pale or no stain, which is all it shows | Dark stain on starch paper; no stain on bleached notes |
The bleached note problem
The most convincing fakes in circulation are printed on real currency paper. Counterfeiters wash the ink off a genuine $5 and print a $100 or $20 image on the blank sheet. The paper feels right, the fibers are real, and a counterfeit pen leaves no stain, because the pen only reacts to starch, which currency paper does not contain.
These notes give themselves away under a light. The thread still reads "USA 5" in the wrong position, and the watermark is a 5 or a Lincoln instead of Franklin or Jackson. That is why the light test, not the pen, is the one to trust.
Say you find a $100 in the till that felt fine and passed the pen. Hold it up to a window. The thread should sit to the left of Franklin and read "USA" and 100; the watermark should be Franklin's face. If you see a large 5 in the watermark space and the thread is to the right, the note is a bleached $5, and it is worth nothing. If the thread and watermark are right but the blue ribbon is printed flat on the surface and the bells do not change to 100s, it is also a fake. If everything matches, tilt the bell in the inkwell: copper to green means you are holding $100.
Common mistakes
- Trusting the pen. A pen passes a bleached genuine note and can be fooled by coated paper. Use it as one check among several, never alone.
- Calling an old note fake because it has no thread. Notes from before series 1990, and every $1 and $2, were made without one.
- Checking a $5 for color-shifting ink. No $5 has ever had it.
- Comparing against the wrong design. A 1996 $100 is genuine without the blue ribbon; its numeral shifts green to black, not copper to green.
- Mistaking a misprint for a fake. Genuine printing errors, such as misaligned or missing printing, are real notes and sometimes valuable; see our guide to misprinted money.
- Mistaking prop money for counterfeit, or the reverse. Film prop notes are usually marked "FOR MOTION PICTURE USE ONLY" or similar. A note with those words is not money and has no face value.
- Spending a suspected fake. Knowingly passing a counterfeit is a federal crime. The loss stays with whoever ends up holding it.
What to do with a suspected counterfeit
The US Secret Service, which investigates counterfeiting, asks for the following:
- Do not give the note back to the person who passed it, unless they become aggressive; your safety comes first.
- If it is safe, delay the person and note their description, any companions, and any vehicle plate number.
- Write your initials and the date in the white border of the note.
- Handle it as little as possible and put it in an envelope.
- Contact your local police or the nearest Secret Service field office, and hand the note only to an identified officer or agent.
Businesses and banks can also report through the Secret Service's online system or with its counterfeit note report form. If the note turns out to be genuine, it is returned. If it is counterfeit, it is kept, and there is no compensation. A bank that receives a counterfeit in a deposit will not credit it.
How WorthPic reads currency photos
WorthPic runs on the newest and most capable AI model available, tuned for exactly this kind of identification. From clear photos of the front and back it reads the denomination, the series year, the design generation, the seal colors and the serial numbers, which tells you which security features the note should have and whether it is an ordinary note at face value or one that collectors pay more for, such as a star note, a low serial or an early series. A photo taken against a light can show whether a watermark and thread appear and in roughly the right place, and a misprint or a printed "MOTION PICTURE" line is usually plain to see. What it cannot know from a photo is how the paper feels, whether the ink is raised, whether the thread is inside the paper or drawn on, what color it glows under UV, or whether the color-shifting ink actually shifts. It identifies and estimates. It does not authenticate notes, grade them or appraise them, and a suspected counterfeit belongs with your bank, the police or the Secret Service.
What to photograph
- The front, flat and straight on, in even daylight, showing the whole note, the series year and both serial numbers.
- The back, flat and straight on.
- The note held against a bright window, front side toward the camera, so the thread and watermark show through.
- The lower right numeral at two different tilts, to show whether it changes color.
- A close up of the portrait and the borders, for fine line detail and microprinting.
- Any oddity close up: a misalignment, a missing print, a star after the serial number, or printed wording that does not belong.
When to get it looked at in person
For an everyday note that passes the light, tilt and touch checks for its design, you need nothing more. For a note that fails any of them, take it to your bank: tellers handle currency all day and can compare it under UV and against genuine notes in minutes. If they suspect a counterfeit, the bank or the police will forward it to the Secret Service. For an old note that is genuine but unusual, such as a large size note, a red seal, a gold certificate or a printing error, a currency dealer or a grading service such as PMG or PCGS Banknote is the right stop, and our guide to the old 100 dollar bill covers the older $100 designs and what they bring.