26 U.S.C. § 2613

(a) Skip person For purposes of this chapter, the term “skip person” means— (1) a natural person assigned to a generation which is 2 or more generations below the generation assignment of the transferor, or (2) a trust— (A) if all interests in such trust are held by skip persons, or (B) if— (i) there is no person holding an interest in such trust, and (ii) at no time after such transfer may a distribution (including distributions on termination) be made from such trust to a nonskip person. (b) Non-skip person For purposes of this chapter, the term “non-skip person” means any person who is not a skip person.