Spotting money laundering comes down to recognizing transactions and behaviors that don’t match economic reality: cash deposits that dodge the $10,000 reporting threshold, customers who can’t or won’t explain where funds came from, businesses generating revenue with no visible operations, and property purchases paid entirely in cash through anonymous entities. The United Nations Office on Drugs and Crime estimates that laundered money accounts for 2% to 5% of global GDP each year, and the patterns below are what investigators and compliance officers look for.
The Three Stages Behind the Red Flags
Laundering moves through three stages, and each one produces its own signals.
Placement is where criminals push physical cash into the financial system. That looks like small deposits spread across accounts, cash fed through currency-heavy businesses, casino play, or outright purchases of expensive items. Layering follows, and this is where the trail gets deliberately tangled: wires between countries, shell companies, rapid buying and selling of investments, chains of transactions built to make the original source impossible to find. Integration is the final step, when the money re-enters the economy looking clean, usually through real estate, luxury goods, or ownership stakes in businesses.
Trade-based laundering deserves its own mention because it hides inside legitimate-looking commerce. An exporter invoices $150,000 for goods worth $100,000. The importer pays the inflated amount, sells the goods at market value, and $50,000 moves across borders as what appears to be normal trade revenue. Under-invoicing does the same thing in reverse. Customs authorities can’t verify the true value of every shipment, which is what makes this scheme work.
Transaction Red Flags
Financial institutions must file a Currency Transaction Report for every cash transaction over $10,000, and criminals know that.1Financial Crimes Enforcement Network. Notice to Customers: A CTR Reference Guide That threshold shapes most of the suspicious behavior you’ll see at the placement stage.
Structuring is the most common tactic. A customer makes several deposits of $9,500 or $9,800 over a few days instead of depositing the full amount at once, with the sole purpose of staying under $10,000. Banks are required to file a Suspicious Activity Report when a transaction involves at least $5,000 and appears designed to evade reporting requirements.2Financial Crimes Enforcement Network. Frequently Asked Questions Regarding Suspicious Activity Reporting Requirements Structuring is itself a federal crime, even when the underlying money is completely legitimate.3Office of the Law Revision Counsel. 31 U.S. Code 5324 – Structuring Transactions to Evade Reporting Requirement Prohibited
Other transaction patterns worth watching:
- Large cash deposits that don’t line up with the customer’s known income, occupation, or type of business.
- Rapid pass-through activity, where money is deposited and then immediately wired out or withdrawn, with the account working as a pipeline rather than a place funds sit.
- Repeated deposits or transfers in round numbers like $5,000 or $9,000 with no obvious business reason.
- Transactions involving jurisdictions on the Financial Action Task Force’s grey or black lists, which identify countries with weak anti-money-laundering controls. As of February 2026, over 20 countries appear on the increased monitoring list.4Financial Action Task Force (FATF). Black and Grey Lists5Financial Action Task Force (FATF). Jurisdictions Under Increased Monitoring – 13 February 2026
Behavioral Red Flags
How someone acts tells you as much as the numbers do. A customer who refuses to provide identification, gives shifting or vague explanations for large transactions, or gets nervous when asked routine questions is signaling something. Compliance officers see this pattern constantly, and it often triggers a deeper look even when the dollar amounts alone wouldn’t stand out.
Third parties are another warning sign. Someone who sends another person to make deposits on their behalf, or who receives unexplained payments from entities with no visible connection to their business, may be hiding who really controls the money. So is a customer who suddenly changes their transaction habits or opens multiple accounts across different branches within a short period.
Attempts to work around procedures are their own red flag. If a customer asks whether a transaction will trigger a report, or tries to persuade an employee to skip a verification step, that’s a deliberate probe of the system. Staff are trained to treat those conversations as suspicious in themselves.
Business and Real Estate Red Flags
Shell companies do most of the heavy lifting in laundering. A business with no employees, no physical office, and no clear product that somehow generates significant revenue exists for one reason. Layered ownership across multiple jurisdictions makes the true owner nearly impossible to identify, which is the whole point.
Legitimate businesses can also serve as fronts. The telltale signs are revenue that doesn’t match the industry or location, cash receipts far above what similar businesses report, and a gap between what a company claims to do and what it actually does. A laundromat or car wash reporting $2 million in annual revenue in a small town is the kind of inconsistency that draws attention.
Real estate is a favorite integration vehicle because a single purchase can absorb a large sum. FinCEN has long required title insurance companies to report all-cash purchases by legal entities in designated metropolitan areas through Geographic Targeting Orders.6Financial Crimes Enforcement Network. Geographic Targeting Order Covering Title Insurance Company In August 2024, FinCEN issued a final rule expanding transparency nationwide, requiring certain professionals involved in closings to report non-financed transfers that carry a high risk for illicit finance.7Financial Crimes Enforcement Network. FinCEN RRE Fact Sheet Red flags include buyers paying entirely in cash through a legal entity, purchase prices well above market value, and properties bought and resold quickly with no apparent renovation.
Cryptocurrency Red Flags
Digital assets have opened newer channels. FinCEN has identified specific indicators that suggest cryptocurrency is being used to launder money.8Financial Crimes Enforcement Network. Advisory on Illicit Activity Involving Convertible Virtual Currency
- Use of mixing or tumbling services, which break the link between sending and receiving wallet addresses and make blockchain tracing harder.
- Rapid conversions between multiple cryptocurrencies with no investment purpose, breaking the chain of custody across different blockchains.
- Transactions involving wallet addresses linked to darknet marketplaces or other known illicit activity.
- Blockchain analytics showing that a wallet sending funds to an exchange has a suspicious origin, such as a known illicit marketplace.
Cryptocurrency exchanges that operate as money services businesses have the same SAR filing obligations as traditional financial institutions. The difference is that blockchain transactions leave a permanent public record, so laundering through crypto is traceable in ways that cash is not, provided someone is looking.
What to Do When You Spot It
Financial institutions must file SARs electronically through FinCEN’s BSA E-Filing System within 30 calendar days of first detecting suspicious activity. If no suspect has been identified at that point, the institution gets an additional 30 days to identify the person, but reporting cannot be delayed beyond 60 days from the initial detection.9Financial Crimes Enforcement Network. FinCEN Suspicious Activity Report Electronic Filing Instructions The institutions required to file include banks, casinos, money services businesses, broker-dealers, mutual funds, insurance companies, and mortgage lenders.
Once a SAR is filed, the institution and everyone involved in the filing are legally prohibited from telling anyone connected to the transaction that a report was made. This tipping-off prohibition covers directors, officers, employees, and agents of the institution, as well as any government employee who learns about the report.10Office of the Law Revision Counsel. 31 U.S. Code 5318 – Compliance, Exemptions, and Summons Authority If a financial institution receives a subpoena for SAR information, it must refuse to produce the report and notify FinCEN. Confidentiality exists because tipping off a suspect would let them destroy evidence, move money, or flee.
Know Your Customer procedures are the earlier line of defense. When you open an account, the institution collects your name, address, date of birth, and identification number, and verifies that information under risk-based procedures.11Financial Crimes Enforcement Network. Exceptive Relief From Requirement to Identify and Verify Beneficial Owners at Each Account Opening For business accounts, the institution must identify each person who owns 25% or more of the entity. These rules exist specifically to make hiding the true owner of funds harder.
Reporting as an Individual
You don’t have to work at a bank to report suspected money laundering. Individuals can contact law enforcement directly or reach the compliance department of the financial institution involved. If you witness potential money laundering at work, federal law gives you protection.
The Anti-Money Laundering Act shields whistleblowers from retaliation, including termination, demotion, and harassment.12Office of the Whistleblower Ombuds. Anti-Money Laundering Act (AMLA) Whistleblowers whose information leads to a successful enforcement action with monetary sanctions exceeding $1 million may be eligible for financial awards of 10% to 30% of the collected sanctions.13Office of the Law Revision Counsel. 31 USC 5323 – Whistleblower Incentives and Protections
One Warning for Cash-Heavy Businesses
Structuring is a crime whether or not the underlying money is dirty.3Office of the Law Revision Counsel. 31 U.S. Code 5324 – Structuring Transactions to Evade Reporting Requirement Prohibited People who deliberately break up cash deposits to avoid a CTR face prosecution even when they had no involvement in any other offense. If you run a business and receive more than $10,000 in cash from a single buyer in one transaction or a series of related transactions, you’re required to file IRS Form 8300 within 15 days.14Internal Revenue Service. Form 8300 and Reporting Cash Payments of Over $10,000 Filing a CTR or an 8300 is routine and doesn’t mean anyone suspects you of a crime; trying to avoid one does.