Bank Secrecy Act of 1970

The Bank Secrecy Act of 1970 requires financial institutions in the United States to assist U.S. government agencies to detect and prevent money laundering. Specifically, the act requires financial institutions to keep records of cash purchases of negotiable instruments, and file reports of cash purchases of these negotiable instruments of $3,000 or more (daily aggregate amount), and to report suspicious activity that might signify money laundering, tax evasion, or other criminal activities.

Helpful Links:
The official page on the Bank Secrecy Act of 1970 on IRS.gov