How do sanctions apply to suppliers and subcontractors?

Screening the named supplier is necessary and not sufficient. Under the OFAC 50 Percent Rule, an entity owned 50 percent or more - in the aggregate, directly or indirectly, by one or more blocked persons - is itself blocked, even though it appears on no list. Aggregate means separate sanctioned holders' stakes are added together rather than assessed individually. Because such an entity is blocked property in its own right, its own holdings are then assessed as a blocked person's holdings: the chain is not diluted by multiplying percentages through it. The EU applies a different test - an ownership criterion of more than 50 percent, plus a separate control criterion that can capture an entity holding less. The UK (OFSI) likewise tests ownership or control. Subcontracting reintroduces the exposure you screened out, so the practical controls are flow-down clauses, mandatory disclosure of sub-tier suppliers, and a contractual right to audit.