The Bank Secrecy Act of 1970 (BSA), also known as the Currency and Foreign Transactions Reporting Act, is a U.S. law requiring financial institutions in the United States to assist U.S. government agencies in detecting and preventing money laundering. Specifically, the act requires financial institutions to keep records of cash purchases of negotiable instruments, file reports if the daily aggregate exceeds $10,000, and report suspicious activity that may signify money laundering, tax evasion, or other criminal activities.

Notably, any individual leaving or entering the United States with $10,000 or more in currency must report it to Customs and Border Protection (CBP). This threshold has never been adjusted for inflation since 1970, which would be equivalent to $82,905 in 2025.

The BSA is sometimes referred to as an anti-money laundering law (AML) or jointly as BSA/AML.

The BSA was originally passed by the U.S. Congress in 1970 and signed by President Richard Nixon into law on October 26, 1970. Shortly after passage, several groups attempted to have the courts rule the law unconstitutional, claiming it violated both Fourth Amendment rights against unwarranted search and seizure, and Fifth Amendment rights of due process. Several cases were combined before the Supreme Court in California Bankers Assn. v. Shultz, 416 U.S. 21 (1974), which ruled that the Act did not violate the Constitution.

Until the 1980s, there was a "prolonged period of inaction", but financial institutions eventually complied with the BSA's reporting requirements.

The statute has been amended several times, including provisions in Title III of the USA PATRIOT Act, which amended the BSA to require financial institutions to establish anti-money-laundering programs by establishing internal policies, procedures, and controls, designating compliance officers, providing ongoing employee training, and testing their programs through independent audits. There was an attempt to include another amendment in 2018, called the Illicit Arts and Antiquities Trafficking Prevention Act (IAATP).

As the name implies, its aim was to restrict illegal trafficking of art in the United States which has the highest rates of money laundering in the world. It was not passed in the United States House of Representatives. This was because the aim of the IAATP did not directly correspond with the aim of the BSA which, according to Congressman Luke Messer, sponsor of the bill, is to "counteract terrorist financing and crack down on terrorist organizations like ISIS".

The Bank Secrecy Act Advisory Group (BSAAG) is a U.S. government–private sector forum established in 1992 by the U.S. Department of the Treasury. Its primary purpose is to enhance collaboration between financial institutions, law enforcement agencies, and regulators in implementing and improving anti-money laundering (AML) policies under the BSA. Over the years, the BSAAG has played a crucial role in shaping U.S. AML regulations and ensuring that the BSA remains responsive to new financial technologies and criminal tactics.

Its recommendations have influenced major reforms, including those stemming from the USA PATRIOT Act and recent updates under the Anti-Money Laundering Act of 2020.

The group supports the Treasury Department's enforcement of the Bank Secrecy Act, which is carried out by the Financial Crimes Enforcement Network (FinCEN).

BSA regulations require all financial institutions to submit five types of reports. Individuals must file an individual filing requirement.

A currency transaction report (CTR) reports cash transactions exceeding $10,000 in one business day, regardless of whether it's in one transaction or several cash transactions. It is filed electronically with the Financial Crimes Enforcement Network (FinCEN) and is identified as FinCEN Form 112 (formerly Form 104).

CTRs include an individual's bank account number, name, address, and social security number. SAR reports, required when transactions indicate behavior designed to elude CTRs (or many other types of suspicious activities), include somewhat more detailed information and usually include investigation efforts on the part of the financial institution to assess the validity or nature of the transactions. A single CTR filed for a client's account is usually of no concern to the authorities, while multiple CTRs from varying institutions or a SAR suggest that activity may be suspicious.