How AML Checks Work on SDA Transactions

Last updated: May 19, 2026

Overview

All SDA transactions are subject to AML (Anti-Money Laundering) screening by Rhino.fi's compliance systems and team. This article explains what happens when a transaction is flagged, how refunds are handled, and what clients can expect in terms of timing and communication.

How AML Blocks Are Signalled

When a transaction is blocked due to an AML alert, you will receive a DEPOSIT_ADDRESS_BRIDGE_REJECTED webhook event with reason: "OPERATION_UNAVAILABLE".

Important: OPERATION_UNAVAILABLE is used exclusively for AML blocks. No other error condition uses this code.

Rhino.fi is not permitted by regulation to disclose to clients that a specific block is AML-related until the investigation is concluded. You may not inform the affected user that their transaction was blocked for AML reasons while the investigation is ongoing.

What Happens Next

All OPERATION_UNAVAILABLE cases are manually reviewed by Rhino.fi's AML compliance officer. The outcome depends on the severity of the alert:

Outcome

Description

Refund

Funds are returned to a user-provided or default refund address after AML review concludes

Seizure

In some cases, regulators require Rhino.fi to seize the funds and transfer them to authorities

In the most common cases (false positives and resolved alerts), funds are refunded. The compliance team will inform you when the case is resolved and whether a refund or seizure applies.

AML Review Timeline

  • Most AML alerts are resolved within 24 hours (Monday–Friday).

  • Complex cases involving legal investigations or regulatory seizure may take longer.

  • For client communication needs (e.g., drafting terms of service), Rhino.fi recommends stating that AML-flagged transactions may be held for up to a defined period pending compliance review. Contact your account manager for a compliance officer consultation.

Refund Address for AML Cases

If a refund is issued after an AML review:

  • The refund address provided by the client or user will be used.

  • Rhino.fi will independently verify the refund address before sending funds.

  • There is no additional compliance risk to the client from providing a user-supplied refund address, as Rhino.fi screens the address prior to the refund.

What You Should NOT Do

  • Do not disclose to users that their transaction was blocked for AML reasons before Rhino.fi gives clearance.

  • Do not request a refund for an OPERATION_UNAVAILABLE case immediately — the compliance team may still be reviewing whether a refund or seizure is appropriate.

False Positive AML Alerts

AML detection systems sometimes produce false positives. If an alert is determined to be a false positive:

  • Rhino.fi may manually reprocess the original transaction rather than issuing a refund.

  • In this case, you will receive a new BRIDGE_ACCEPTED followed by BRIDGE_EXECUTED event — with a different _id from the original REJECTED event.

  • Your system must be able to handle BRIDGE_ACCEPTED arriving after a prior REJECTED event for the same deposit.