A large cash deposit most likely reflects money laundering when it is 1. from a customer who has never conducted a transaction in cash before. 2. transacted in segments smaller than the reporting thresholds at various times during the day. 3. followed by an immediate wire transfer to an offshore secrecy haven. 4. by a customer who operates a cash-based business.

A large cash deposit is most indicative of money laundering when combined with other red flags that suggest an attempt to conceal the nature, source, or control of the funds. A sudden change in a customer's transaction behavior (1) is a primary indicator of potentially unusual activity. Structuring transactions to fall below reporting thresholds (2) is a classic money laundering technique designed to evade regulatory scrutiny. Immediately wiring the funds to an offshore secrecy haven (3) is a common method used in the layering stage to obscure the audit trail and move funds out of reach. These three scenarios, especially in combination, are strong indicators of potential money laundering.

4. by a customer who operates a cash-based business. This is not inherently suspicious. Legitimate cash-intensive businesses (e.g., restaurants, retail stores) are expected to make large cash deposits as part of their normal course of business.

1. ACAMS CAMS6 Study Guide (6th Edition). Chapter 2, "The International AML/CFT Framework," describes the stages of money laundering. Structuring (smurfing) is detailed as a key part of the placement stage (p. 53). The immediate transfer of funds, especially offshore, is characteristic of the layering stage (p. 54). Chapter 3, "AML/CFT Compliance Programs," identifies "deviations from normal or expected activity" as a fundamental basis for identifying suspicious transactions (p. 105).

2. Financial Action Task Force (FATF). (2012). International Standards on Combating Money Laundering and the Financing of Terrorism & Proliferation – The FATF Recommendations. Interpretive Note to Recommendation 10 (Customer Due Diligence) requires financial institutions to monitor transactions to ensure they are consistent with the institution's knowledge of the customer and their business profile. A sudden, large cash deposit from a non-cash customer would be inconsistent.

3. Financial Action Task Force (FATF). (2014). Guidance for a Risk-Based Approach for the Banking Sector. Annex 2 provides examples of suspicious transaction indicators. It lists "Structuring of deposits, withdrawals or purchase of monetary instruments below a certain threshold to avoid reporting" and "Transactions involving countries that are known for high levels of corruption, organised crime, or drug production/trafficking" (p. 48-49).

4. FinCEN. (2020). FinCEN Advisory on COVID-19-Related Medical Scams. FIN-2020-A002. While specific to a context, this official advisory reinforces the principle of identifying red flags, noting that criminals may "leverage cash-intensive businesses" but that the indicator is activity "not commensurate with the level and nature of the business." This supports that a cash deposit from a cash business is only suspicious when it is inconsistent with the expected profile, not on its own.