A Suspicious Activity Report (SAR) is a report that financial institutions like banks file with the U.S. government regarding questionable customer transactions that could potentially indicate money laundering, tax evasion, fraud, or other illegal financial activities. SARs are filed with the Financial Crimes Enforcement Network (FinCEN), a bureau of the U.S. Department of the Treasury. https://lawforeverything.com/what-is-a-suspicious-activity-report-sar/