Wyo. Stat. § 2-3-818: Insubstantial allocation not required.

(a) If a trustee determines that an allocation between principal and income required by W.S. 2-3-819 through 2-3-822 or 2-3-825 is insubstantial, the trustee may allocate the entire amount to principal unless one of the circumstances described in W.S. 2-3-804(c) applies to the allocation. This power may be exercised by a cotrustee in the circumstances described in W.S. 2-3-804(d) and may be released for the reasons and in the manner described in W.S. 2-3-804(e). An allocation is presumed to be insubstantial if:

(i) The amount of the allocation would increase or decrease net income in an accounting period, as determined before the allocation, by less than ten percent (10%); or

(ii) The value of the asset producing the receipt for which the allocation would be made is less than ten percent (10%) of the total value of the trust's assets at the beginning of the accounting period.