Section 2621. Taxable amount in case of taxable distribution (a) In general

-For purposes of this chapter, the  taxable  amount  in  the case of any taxable distribution shall be-
    (1) the value of the property received by the transferee, reduced by
    (2)  any  expense  incurred  by  the transferee in connection with the
  determination, collection, or refund of the tax imposed by this  chapter
  with respect to such distribution.
    (b)  Payment  of GST tax treated as taxable distribution.-For purposes
  of this chapter, if any of the tax imposed by this chapter with  respect
  to any taxable distribution is paid out of the trust, an amount equal to
  the portion so paid shall be treated as a taxable distribution.