31 CFR §594.406

1. (a)Except as provided in § 594.207, the prohibitions on transactions or dealings involving blocked property contained in §§ 594.201 and 594.204 apply to services performed in the United States or by U.S. persons, wherever located, including by an overseas branch of an entity located in the United States:
   1. (1)On behalf of or for the benefit of a person whose property or interests in property are blocked pursuant to § 594.201(a); or
   2. (2)With respect to property interests subject to §§ 594.201 and 594.204.
2. (b)Example: U.S. persons may not, except as authorized by or pursuant to this part, provide legal, accounting, financial, brokering, freight forwarding, transportation, public relations, educational, or other services to a person whose property or interests in property are blocked pursuant to § 594.201(a).