26 USC §2661

Insofar as applicable and not inconsistent with the provisions of this chapter— (1) except as provided in paragraph (2), all provisions of subtitle F (including penalties) applicable to the gift tax, to chapter 12, or to section 2501, are hereby made applicable in respect of the generation-skipping transfer tax, this chapter, or section 2601, as the case may be, and (2) in the case of a generation-skipping transfer occurring at the same time as and as a result of the death of an individual, all provisions of subtitle F (including penalties) applicable to the estate tax, to chapter 11, or to section 2001 are hereby made applicable in respect of the generation-skipping transfer tax, this chapter, or section 2601 (as the case may be).