Blocking is the US sanctions action of freezing a prohibited party's property and interests in property that come within reach, then holding and reporting it rather than returning or processing it. It is how OFAC sanctions are actually enforced against SDNs and entities caught by the 50 Percent Rule.
What is blocking, in plain English?
Blocking is the specific action a US firm takes when a transaction or account touches a party OFAC has sanctioned. Instead of sending the money back or letting it through, the firm holds the funds, places them in a segregated blocked account, and reports the block to OFAC. The property is frozen in place while legal ownership stays with the sanctioned party.
It applies to property and interests in property of the target that come within US jurisdiction, which is broader than it sounds. It covers not just accounts in the target's exact name but interests held through entities they own, notably anything caught by the 50 Percent Rule. Blocking is the enforcement teeth behind the SDN List.
The single most important thing to get right is knowing when to block versus when to reject. They are different legal actions with different outcomes, and confusing them is one of the most common and costly sanctions mistakes.
Block vs reject
What changes | Reject | Block |
Funds | Declined and returned to sender. | Held and frozen, not returned. |
Account | No funds retained. | Funds placed in a segregated blocked account. |
Reporting | Rejection report filed. | Blocking report filed within the deadline. |
When used | Certain prohibited transactions with no blockable interest. | Property of an SDN or 50 Percent Rule entity. |
Who is involved
Who | Their role |
OFAC | Publishes the lists and rules, receives blocking reports, and grants licenses. |
The firm | Detects the hit, blocks the property, segregates it, and files the report on time. |
Sanctions analyst | Confirms the match, decides block versus reject, and documents the rationale. |
The customer or sender | Party whose transaction is stopped; may hold the underlying interest that is blocked. |
What it looks like in practice
In practice
A wire arrives naming a beneficiary that screening matches to an entity majority-owned by an SDN. The analyst confirms the ownership chain and determines this is a blockable interest under the 50 Percent Rule, not a case for rejection.
The firm holds the funds, moves them into a segregated blocked account, stops the payment from settling, and files a blocking report to OFAC within the required window. The money is not sent back to the originator and is not delivered to the beneficiary. It stays frozen until OFAC de-lists the party or issues a license.
Why it matters to operators
Getting the block-versus-reject call wrong cuts both ways, and both are violations. Rejecting when you should block lets property leave the institution that the law required you to hold, so you have released blockable funds. Blocking when you should reject, or failing to report either action on time, is also a breach. The action is not a judgment call you can wing; it follows from the specific list, party, and transaction.
On top of the decision, operators have to handle blocked funds correctly: segregate them, keep them untouched, and file the report within the deadline. A block that is not reported, or funds that get commingled or quietly released, undoes the whole point of the control.
What to watch in the data
- Block vs reject logic. The decision should map to the list and interest at play, not to analyst habit; document why each time.
- 50 Percent Rule reach. Interests held through majority-owned entities are blockable even when the entity itself is not named.
- Segregated funds. Blocked property must sit in a dedicated blocked account, never mixed with operating balances.
- Reporting deadlines. A correct block with a missed filing window is still a violation; track the clock on every block.
- No quiet release. Blocked funds do not move without a license; watch for any attempt to return or process them.
Quick questions
What is the difference between blocking and rejecting?
Blocking means holding and freezing the funds and reporting them; the money does not move. Rejecting means declining the transaction and returning the funds to the sender, with no property held. The right action depends on the specific list and interest involved.
Is blocking the same as an asset freeze?
Blocking is the US mechanism for carrying out an asset freeze. The broader concept of freezing applies across jurisdictions; blocking is OFAC's specific term and process, including segregation and mandatory reporting.
What happens to blocked funds?
They sit in a segregated blocked account, frozen and untouched. The sanctioned party retains ownership but has no access. The funds stay there until OFAC de-lists the party or grants a license authorizing a specific action.
Why is confusing block and reject so costly?
If you reject when you should have blocked, you let property leave the institution that the law required you to hold, which is a violation. The two actions have different legal effects, so the choice has to be made deliberately and documented.
Does the 50 Percent Rule affect blocking?
Yes, heavily. Property of an entity that is 50 percent or more owned by one or more SDNs is blockable even if that entity is not itself named on the list. Missing these indirect interests is a common source of failed blocks.
Go deeper
- OFAC, US Treasury ↗ — Administers US sanctions programs, the SDN list, and licensing.
- European Banking Authority ↗ — EU banking regulator. Strong Customer Authentication under PSD2 and AML guidance.