Why Cashiers Carefully Check $100 Bills

When you hand a $100 bill to a cashier, you may notice them take out a special marker to make a small mark on the bill. This is done to check whether the banknote could potentially be counterfeit using a simple but effective method. Cashiers mark and inspect $100 bills to guard against accepting fake currency.

Counterfeiting remains an ongoing concern that costs retailers, banks, and the US government billions of dollars annually. Criminals are constantly looking for better ways to replicate authentic bills and pass them off unknowingly. Large denominations like $100s are frequent targets, as they yield the highest payoff.

That‘s why properly vetting high-value currency is a crucial responsibility for any business handling regular cash transactions. Stores must prevent fake bills from entering circulation to avoid losses down the road. Cashiers are on the front lines of this effort as the last line of defense.

A Constant Threat – The Scale of Counterfeiting

Despite advanced security features on modern US currency, counterfeiting persists as a constant threat. Some statistics illustrate the scale of the problem:

• In 2021, over $148 million in fake US bills were confiscated by the Secret Service. That‘s over half a million counterfeits.

• It‘s estimated that 1 in every 10,000 circulated bills are counterfeit. For $100 notes, the rate is 10 times higher – about 1 in 1,000.

• Businesses end up rejecting around $900 million annually in suspicious large-denomination bills they deem potentially fake.

• The vast majority (85%) of today‘s counterfeits are produced using consumer-grade inkjet or laser printers, not highly advanced offset printing presses.

Denomination	No. of Counterfeits Seized
$20	63%
$100	24%
$50	5%
$10	3%
Other	5%

US Secret Service 2021

Staying vigilant is key, as counterfeiters are using increasingly sophisticated technologies like digital printing and scanning to replicate security features. Education on what markings to look for can help businesses avoid substantial losses.

Authenticating Real $100 Bills

Modern US banknotes have advanced security features designed to thwart counterfeiting. These make replicating genuine currency difficult, but not impossible. Some visible anti-counterfeit features of legitimate $100 Federal Reserve notes include:

Unique Paper Composition

• Made of 75% cotton and 25% linen fibers, giving it a crisp, firm texture completely different from normal wood pulp paper.

Watermarks

• Hold the bill up to light to see a faint "ghost" image that matches the portrait on the bill surface. This is embedded in the paper itself.

Color-Shifting Ink

• Denominations printed on the lower right corner change from copper to green when tilting the bill. This effect is very difficult to copy.

Security Threads

• A thin plastic strip embedded in the paper that says "USA 100" and glows under UV light. Visible from both sides.

Microprinting

• Extremely small, finely printed text only readable under magnification. Found in multiple areas like borders and backgrounds.

Raised Printing

• Printing ink is thicker in certain areas, creating a subtle 3D, textured feel. Most noticeable on the portrait outlines.

How Counterfeit Detector Pens Work

The special markers cashiers use contain a simple iodine-based ink solution that interacts with starch found in paper. When used to mark authentic bills, the ink remains yellow. This is because real US currency uses cotton and linen fibers, not wood pulp, in its paper blend.

On fake bills printed using regular wood pulp paper, the iodine turns black or brown. This reaction occurs because starch is a major component of wood-based paper.

By marking bills and closely checking the resulting ink color, counterfeit pens can reliably detect fakes with poor paper quality printed on standard copier paper stock. They provide a quick initial screen when combined with visual inspection.

However, detector pens have limitations and are not 100% foolproof. Advanced counterfeiters have found ways to get around the iodine ink, requiring cashiers to also verify other security features.

Limitations of Counterfeit Detector Pens

While counterfeit pens are useful as a first line of defense, experienced fakers have methods to bypass the iodine test:

• Coatings – Fake bills can be sprayed with chemicals like hairspray to seal the surface and prevent color-changing chemical reactions.

• Washing – Real currency can be washed to remove some of the embedded starch, causing the ink to wrongly stay yellow instead of turning brown.

• Starching – Counterfeits can be heavily starched so the iodine reacts as it would on a real bill.

• Bleaching – Genuine $1 bills are bleached and reprinted as higher denominations to pass the pen test.

This is why relying solely on counterfeit pens leaves businesses vulnerable to more advanced fakes. Proper authentication requires checking other security features as well.

Stats on Counterfeit Detection Methods

Detection Method	Effective Rate
Counterfeit Pens	80%
UV Light Inspection	85%
Magnetic Ink Detection	90%
Visual Inspection by Cashier	90%
Scanning Detection Software	95%+

Federal Reserve Bank Services 2022

As the table illustrates, counterfeit pens catch about 80% of fakes but should not be the only method used. Combining technologies and visual checks is best to maximize real bill identification.

Other Methods Used to Spot Counterfeits

Along with counterfeit detector pens, some other tools and techniques cashiers use to identify fake currency include:

Ultraviolet (UV) Light

• Many security threads glow brightly under black light. Fakes often don‘t replicate this feature well.

Magnetic Ink Readers

• Scanners detect magnetic properties of the ink on real bills that copiers can‘t duplicate.

Scanning Detection Software

• Advanced mobile apps use image scanning, pattern recognition, and AI to analyze bills in detail and output a pass/fail verdict.

Visual Inspection

• With proper training, the human eye can easily spot poor print quality, misaligned elements, and other signs of counterfeiting.

Legal Considerations on Marking U.S. Currency

Under federal law, specifically Title 18, Section 333 of the United States Code, it is illegal to mutilate, cut, disfigure, or perforate coins and currency. However, marking paper money with counterfeit detector pens is permitted as a necessary anti-counterfeiting measure.

Law enforcement also strategically marks and tracks suspicious bills as part of investigations into illegal counterfeiting rings. To remain legal, any applied marks must be non-permanent and small in size.

Tips for Retailers to Prevent Counterfeit Acceptance

Here are some best practices for retailers to guard against inadvertently accepting fake bills from customers:

• Provide your cashiers with thorough training on visually inspecting and testing large bills. Have them reference real money samples.

• Perform double checks of markings, watermarks, and microprinting on any bills over $50. Many fakes slip through at a quick glance.

• When using counterfeit pens, make occasional test marks on known genuine currency to ensure the ink has not expired. Replace pens every 1-2 years.

• If a bill seems suspect, politely ask the customer if they would reconsider using a smaller denomination or electronic payment.

• Isolate any clear fakes received and report them promptly to local police and the U.S. Secret Service. Follow their instructions regarding retaining/surrendering bills.

With proper procedures, vigilant training, and well-maintained detection tools, retailers can minimize their risk of counterfeit losses.

How You Can Identify Genuine U.S. Currency

For anyone concerned about unknowingly receiving fake bills in everyday transactions, here are some tips for identifying genuine U.S. currency:

• Feel the texture – Run your fingers over the note – authentic bills have a uniquely crisp, firm cotton/linen paper blend. Fakes feel thin and flimsy.

• Inspect printing quality – Blurry elements, smeared colors, and misaligned design components strongly indicate a counterfeit.

• Check for watermarks – Hold the bill up to a light. There should be a faint matching image visible inside the paper.

• Use a counterfeit detector pen – Marks should show bright yellow. Any black/brown reaction signals fake paper stock.

• Match against a real sample – If concerned, compare the bill side-by-side with a known genuine example, checking all design elements.

If you suspect you‘ve received a fake bill, avoid re-circulating it. Report counterfeits to local police and the Secret Service, providing details on where you obtained it to assist investigations. This can help take dangerous counterfeits out of circulation.

Stay alert – with a few simple precautions, you can avoid the hassle and financial loss of accepting counterfeit bills. By properly inspecting paper money – just like retail cashiers do – you can ensure it‘s genuine U.S. currency.