**Cash Tracking: You Have Surveillance Instruments in Your Wallet**
It’s waiting in your wallet for its deployment. For years it has been circulating and reporting its location whenever it gets scanned – which happens quite often. It can make your interests and needs traceable, reveal personal connections and business relationships.
It’s a banknote, a printed strip of cotton fibers with two letters and a ten-digit number chain in the upper right corner on its back – its unique serial number. Perhaps an exemplary twenty-euro note. Throughout its life, it will be registered at countless positions. It passes through machines for tickets, parking receipts, snacks, coffee, cigarettes, photos or gambling, and repeatedly through devices that count, check and sort money. Machines with modern banknote processing modules can track serial numbers.
Even when a human collects the banknote, it’s not protected from automated serial number recognition. Because the revenues of most businesses are collected daily by cash transport companies. And they run the money through banknote checking and sorting machines in their cash centers, which can also read serial numbers.
The comprehensive use of automated serial number recognition provides the technical infrastructure for detailed tracking of banknotes’ journeys. And there are increasing efforts to store and combine the resulting data. Cash is thus becoming a surveillance instrument.
**Current Uses of Cash Tracking**
Law enforcement agencies already use serial number tracking for investigations. The industry wants to optimize cash logistics with it. And curious people also track cash as a leisure activity. “Because it’s fun!” says a website for passionate Euro banknote trackers.
There are many payments that some people prefer to handle anonymously: expenses for health problems or sexual activities, for example, but also donations to political organizations. If the bill that a high official withdrew today appears tomorrow in a workplace for sex workers, that could make him blackmailable. If an uncloseted person supports a queer NGO with a tracked banknote, that could threaten their existence in some places.
**Cash Remains Popular – Also for Privacy Reasons**
Over 80 percent of Germans see data protection as an argument for cash payments. More than two-thirds believe that cash has high importance for society. According to the most recent survey, over half of all payment transactions were still handled with cash in 2023. People in Germany hoard 395 billion euros in cash.
Data protection advocates warn of a new form of mass surveillance and the immense fundamental rights violation that cash tracking potentially represents. The Bundesbank points out that privacy protection is an important advantage of cash for many people. People in Germany have a right to informational self-determination. The German central bank itself tracks the path of certain banknotes on certain occasions. “It can be assumed that serial number reading will establish itself permanently and irreversibly,” it writes in an internal document from 2021.
**International Cash Tracking Systems**
In China, ATMs must assign the serial number of every banknote they dispense to an account. This makes it clear who put each note into circulation. Some devices even capture biometric data of the withdrawing person.
In South Africa, the central bank operates real-time tracking of cash movements. Information from ATMs is collected in a central database and shared with security authorities. Since this has been happening, there have been more arrests, for example after ATM bombings.
The Canadian central bank maintains a database with data on all Canadian banknotes in circulation to track wear and tear. The Bank of Israel also has a banknote database.
In the USA, a consortium of 10,800 US law enforcement agencies called Regional Information Sharing Systems (RISS) operates a network of money counting machines and a database where captured banknotes are stored with photos and serial numbers.
**German Police Use of Cash Tracking**
German police have been using serial numbers of banknotes to track cash flows since at least the 1970s. This might look like: A person is kidnapped, the kidnappers make a ransom demand. But before the money is handed over in a suitcase, police officers record the serial numbers of the bills to be handed over in a police database.
The serial numbers are also linked to people in the police database. “In the police information network, the linking of various information categories is possible, including personal data,” writes Bremen police.
That means: There are police-known banknotes circulating out there. And it’s possible that you have one of them in your wallet.
**Private Sector Innovation: Elephant & Castle IP**
Gerrit Stehle, managing director of Elephant & Castle IP GmbH, wants to lift official cash tracking in Germany to a new level. Stehle offers a constant, automated mass comparison with circulating banknote serial numbers.
His company receives banknote serial numbers with location and time of capture from one of the cash transport companies operating in Germany. Stehle researches in this database for security authorities as an expert. He already works with several German public prosecutor’s offices and also with security authorities from other countries.
“Our technology makes it possible to trace the history of banknotes at the push of a button,” says Stehle. “We ‘listen’ to the cash, so to speak.”
**Future Concerns and Developments**
Stehle’s goal is to make his system directly accessible to investigators through paid software licenses. Without going through the expert. “Through a user-friendly interface, they could then connect to the system 24/7 and perform the corresponding evaluations independently,” says Stehle.
**Privacy Concerns**
Data protection officer Marit Hansen from Schleswig-Holstein sees comprehensive cash tracking critically: “When serial numbers are stored with time and location of capture and this data is collected in increasingly granular detail, one loses the anonymity of cash.”
Hansen compares the serial numbers to printer IDs, so-called Yellow Dots, contained in color printouts. “These are also initially just technical data and yet they can be used, for example, to identify whistleblowers.”
The article concludes by noting that comprehensive cash tracking could fundamentally change the anonymous nature of cash payments, turning what many consider a fundamental privacy tool into a surveillance instrument.
