Sec. 21. For purposes of section 16 of this chapter, the net fair market values of the assets held in trust on the first business day of a proper valuation year shall be adjusted to reflect any:
(1) reduction, in the case of a distribution or payment; or
(2) increase, in the case of a receipt;
for the prior valuation year as if the distribution, payment, or receipt had occurred on the first day of the prior valuation year.