If a trustee determines that an allocation between principal and income required by section 68-10-409, 68-10-410, 68-10-411, 68-10-412 or 68-10-415, Idaho Code, is insubstantial, the trustee may allocate the entire amount to principal unless one (1) of the circumstances described in section 68-10-104(c), Idaho Code, applies to the allocation. This power may be exercised by a cotrustee in the circumstances described in section 68-10-104(d), Idaho Code, and may be released for the reasons and in the manner described in section 68-10-104(e), Idaho Code. An allocation is presumed to be insubstantial if:
(1) 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
(2) 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.