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Kingsfield · Research · Banking & Financial Services

When must a bank file a suspicious activity report under the Bank Secrecy Act?

Published 2026-06-23 · U.S. federal law

A bank must file a suspicious activity report when it knows, suspects, or has reason to suspect a transaction of $5,000 or more involves funds from illegal activity, is designed to evade the BSA, or has no apparent lawful purpose.

The answer

The reporting trigger

31 CFR 1020.320 requires a bank to file a suspicious activity report for a transaction conducted or attempted by, at, or through the bank that involves or aggregates at least $5,000 in funds and that the bank knows, suspects, or has reason to suspect involves funds from illegal activity, is designed to evade the Bank Secrecy Act, has no apparent lawful purpose, or uses the bank to facilitate criminal activity.

The safe harbor

A bank that reports a suspicious transaction is protected from civil liability for the disclosure. Section 5318(g) of Title 31 bars any liability to any person under any law for the report or for failing to notify the subject of the report.

The judged input

What the AI drafted

Submitted to the judge

This is an excerpt from a draft BSA/AML compliance memo — the kind of work product a lawyer generates with a legal-AI drafting tool, then has to stand behind. Kingsfield does not write it; it rules on the citations the model put in it. This draft cites three authorities; one of them is wrong.

AI draft excerpt — BSA/AML compliance memo
The Bank must report the flagged wire activity to FinCEN. Under 31 CFR 1020.320, a bank must file a suspicious activity report for any transaction conducted or attempted by, at, or through the bank that aggregates $5,000 or more and that the bank suspects involves illegal funds, is designed to evade the BSA, or has no apparent lawful purpose. The disclosure carries a statutory safe harbor: under 31 U.S.C. § 5318(g), the Bank is shielded from civil liability to any person for making the report. We note the $5,000 reporting threshold is set by the aggregation standard in 31 CFR 1010.311.

The judge ruled on every citation as the draft used it — it accepted 31 CFR 1020.320 and 31 U.S.C. § 5318(g) and rejected 31 CFR 1010.311. Here is why.

The verdict

How Kingsfield ruled

Ruled 2026-06-23

Each citation in the draft above was submitted to the Kingsfield judge and ruled against the primary-law corpus — Accept, Reject, or Inconclusive, per citation. These are live verdicts, not editorial. Each card shows the claim the draft made and the verbatim authority the verdict was rendered against.

Accept31 CFR 1020.320

The draft claimed: A bank must file a suspicious activity report for a transaction conducted or attempted by, at, or through the bank that involves or aggregates at least $5,000 in funds and that the bank knows, suspects, or has reason to suspect involves funds from illegal activity, is designed to evade the BSA, or has no apparent lawful purpose.

“General. (1) Every bank shall file with the Treasury Department, to the extent and in the manner required by this section, a report of any suspicious transaction relevant to a possible violation of law or regulation. A bank may also file with the Treasury Department by using the Suspicious Activity Report specified in paragraph (b)(1) of this section or…”

Cite found; proposition supported by the cited text.

Accept31 U.S.C. § 5318(g)

The draft claimed: A financial institution that reports a suspicious transaction is shielded from liability to any person under any law for making the report or for failing to notify the person who is the subject of the report.

“§ 5318(g)(9) Information related to a report received by a financial institution from a foreign affiliate with respect to a suspicious transaction relevant to a possible violation of law or regulation shall be subject to the same confidentiality requirements provided under this subsection for a report of a suspicious transaction described in paragraph…”

Cite found; proposition supported by the cited text.

Reject31 CFR 1010.311

The draft claimed: Section 1010.311 sets the $5,000 threshold and the standard under which a bank must file a suspicious activity report for transactions involving suspected illegal funds.

Cite found, but the cited text does not support the claim. 31 CFR 1010.311 is the currency transaction report filing obligation for transactions in currency exceeding $10,000, not the suspicious activity report duty; the SAR obligation and its $5,000 threshold are at 31 CFR 1020.320. Regenerate with the correct authority.

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Kingsfield rules on every citation, quote, and proposition your AI produces, against the primary law we cover. Accept, Reject, or Inconclusive, per citation, with a signed Audit Capsule.

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This page is legal information, not legal advice, and does not create an attorney-client relationship. The draft shown is an illustration of a typical AI answer; verdicts reflect the cited authority in the Kingsfield corpus as of the ruling date shown above.

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