Suspicious activity report (SAR)
A suspicious activity report (SAR) is the confidential filing a US financial institution makes to FinCEN when it identifies transactions that may involve money laundering, fraud, or other illicit activity. Institutions generally must file within 30 calendar days of detecting the activity, and they are prohibited from telling a customer that a SAR was filed. SAR filing is a core Bank Secrecy Act obligation.
By Krisan Nichani, Chief Compliance OfficerLast updated July 2026
SARs sit at the end of the monitoring pipeline: rules fire alerts, analysts investigate, and when suspicion holds, the institution files a report with a narrative explaining what was seen and why it matters. The filing itself is a form; the cost is the investigation behind it — gathering the counterparty file, transaction history, and supporting records into a case a regulator can examine.
Infinite Agents assembles and documents each case before an analyst opens it, with every decision made by a human — so the path from alert to disposition, including SAR-worthy cases, produces reviewed, defensible files instead of a backlog.
Frequently asked questions
Who files suspicious activity reports?
Institutions with Bank Secrecy Act obligations — banks, money services businesses, broker-dealers, and others. Reports go to FinCEN, which makes them available to law enforcement. Bank Secrecy Act (BSA)
How long does a bank have to file a SAR?
No later than 30 calendar days after initially detecting facts that may require a filing. If no suspect is identified, the institution may take up to 30 more days — but never more than 60 total. Continuing activity is typically re-reported on a roughly 90-day cycle.
Does a SAR mean the customer committed a crime?
No. A SAR reports suspicion, not a conclusion — law enforcement decides whether to pursue it. Filing is confidential, and the institution may not disclose it to the customer. AML transaction monitoring
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