How to File a SAR as a Money Services Business

Filing a Suspicious Activity Report (SAR) is one of the most important — and most misunderstood — obligations for a Money Services Business. FinCEN requires MSBs to report transactions that the business “knows, suspects, or has reason to suspect” involve funds derived from illegal activity, are designed to evade BSA reporting requirements, or have no apparent business or lawful purpose.

For crypto MSBs, SAR filing is where your transaction monitoring, case management, and compliance documentation all come together. Here’s how the process actually works.

When to File

An MSB must file a SAR when a transaction meets both of these conditions:

1. The transaction involves $2,000 or more (either individually or in aggregate)
2. The MSB knows, suspects, or has reason to suspect that the transaction:
   • Involves funds from illegal activity
   • Is designed to evade BSA reporting requirements (structuring)
   • Has no apparent business or lawful purpose
   • Involves the use of the MSB to facilitate criminal activity

The $2,000 threshold is lower than the $5,000 threshold that applies to banks and broker-dealers. This is specific to MSBs.

Important Clarification from FinCEN (October 2025)

In October 2025, FinCEN issued updated FAQs that clarified several points about SAR filing:

• Structuring SARs: You are not required to file a structuring SAR simply because a transaction is near a reporting threshold. There must be additional information suggesting the transactions were designed to evade reporting requirements.
• Continuing activity reviews: After filing a SAR, you are not required to manually review a customer or account to determine whether suspicious activity has continued. Your existing monitoring systems and controls are sufficient.
• Documenting non-filings: There is no explicit legal requirement to document your decision not to file a SAR. A concise internal statement is generally sufficient if you choose to document it.

These clarifications are significant for smaller MSBs that were over-filing or spending excessive time on continuing reviews. The emphasis is on risk-based judgment, not mechanical filing.

The Filing Timeline

Once your compliance team identifies suspicious activity, the clock starts:

• 30 calendar days from the date of initial detection to file the SAR
• If no suspect is identified at the time of detection, you may extend this by an additional 30 calendar days (to identify the suspect), but filing cannot be delayed beyond 60 calendar days from initial detection
• “Initial detection” means the point at which your transaction monitoring system or compliance team first identifies the activity as potentially suspicious — not the date the transaction occurred

Missing the filing deadline is itself a BSA violation and can result in penalties during an examination.

How to File: Step by Step

Step 1: Detect and Investigate

Your transaction monitoring system flags an alert. Before filing a SAR, conduct a review:

• Pull the customer’s transaction history and account information
• Look for patterns — structuring, rapid movement of funds, transactions with high-risk jurisdictions or sanctioned entities
• Check whether the activity has a plausible business explanation
• Document your investigation, including what you reviewed and what you found

Not every alert requires a SAR. The investigation step is where you apply judgment.

Step 2: Prepare the SAR Filing

SARs are filed electronically through FinCEN’s BSA E-Filing System. The form has several sections:

Filing Information (Part I):

• Filing type (initial, continuing, corrected)
• Filing institution information

Subject Information (Part II):

• Name, address, date of birth, and identification information for the individual or entity involved
• If the subject is unknown, indicate that the subject could not be identified
• For crypto transactions, include wallet addresses, transaction hashes, and any relevant blockchain data in the narrative

Suspicious Activity Information (Part III):

• Date range of the suspicious activity
• Total dollar amount involved
• Type of suspicious activity (check the applicable categories — there are specific checkboxes for virtual currency activity)
• The instruments or mechanisms used

The Narrative (Part V): This is the most important section. The narrative should answer the five Ws:

• Who is conducting the suspicious activity?
• What instruments or mechanisms are being used?
• When did the activity occur (specific dates and timeframe)?
• Where did the activity take place?
• Why is the activity suspicious?

Write the narrative in clear, factual language. Avoid speculation or legal conclusions. Describe what happened, what made it unusual, and why it doesn’t have an apparent legitimate purpose.

For crypto-specific SARs, include:

• Wallet addresses (full addresses, not truncated)
• Transaction hashes
• Blockchain network (Bitcoin, Ethereum, etc.)
• Exchange or platform names
• IP addresses if available
• Any blockchain analytics findings (e.g., connections to known illicit wallets)

Step 3: File Electronically

Submit the SAR through FinCEN’s BSA E-Filing System at https://bsaefiling.fincen.treas.gov. You’ll receive a confirmation with a BSA ID number. Retain this for your records.

Step 4: Maintain Records

Keep a copy of the SAR and all supporting documentation for five years from the date of filing. This includes:

• The filed SAR form
• Investigation notes and findings
• Transaction records related to the suspicious activity
• Any communications related to the investigation

Confidentiality Requirements

SAR filings are confidential. You cannot disclose to the subject of the SAR that a report has been filed. This is a legal prohibition under the BSA, and violating it (known as “tipping off”) can result in criminal penalties.

This means:

• Don’t tell the customer a SAR was filed
• Don’t include SAR-related information in responses to customer inquiries
• Limit internal access to SAR information to those who need it for compliance purposes
• Be careful with subpoenas — SAR information has specific legal protections

Continuing SARs

If suspicious activity continues after you file an initial SAR, you should file a continuing SAR. FinCEN guidance suggests reviewing for continuing activity at least every 90 days after the initial filing.

The October 2025 FAQ clarification is relevant here: you are not required to conduct a manual review after every SAR filing. Your existing monitoring systems and controls are sufficient to detect continuing activity.

Common Mistakes

• Filing too late. The 30-day clock starts at detection, not at the end of your investigation. If you need more time to investigate, start the SAR and file what you have within 30 days.
• Weak narratives. A narrative that says “transaction appeared suspicious” without explaining why is insufficient. Be specific about the red flags, patterns, and facts.
• Missing crypto-specific details. For virtual currency SARs, include wallet addresses and transaction hashes. FinCEN has specifically requested this data to support law enforcement investigations.
• Over-filing defensively. Filing SARs on every transaction that’s slightly unusual wastes compliance resources and dilutes the value of the reports. Apply risk-based judgment.
• No supporting documentation. If an examiner asks about a SAR filing, you need to be able to produce the investigation file, not just the filed form.

Making SAR Filing Less Painful

The SAR filing process is manual and time-consuming, especially when you’re compiling transaction data, drafting narratives, and navigating the BSA E-Filing interface. For crypto MSBs processing high volumes of transactions, this doesn’t scale.

Decern is building tooling to automate the heavy lifting — from case management that tracks investigations to SAR generation that pre-fills forms and drafts narratives from your transaction data. The goal is to reduce the time from alert to filing while keeping your compliance team in control of the final review.

This article is for informational purposes only and does not constitute legal advice. Consult a qualified compliance attorney for guidance specific to your SAR filing obligations.