26 U.S.C. § 2621

1. (a)For purposes of this chapter, the taxable amount in the case of any taxable distribution shall be—
   1. (1)the value of the property received by the transferee, reduced by
   2. (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.
2. (b)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.