Tex. Prop. Code § 116.171

If a trustee determines that an allocation between principal and income required by Section 116.172, 116.173, 116.174, 116.175, or 116.178 is insubstantial, the trustee may allocate the entire amount to principal unless one of the circumstances described in Section 116.005(c) applies to the allocation. This power may be exercised by a cotrustee in the circumstances described in Section 116.005(d) and may be released for the reasons and in the manner described in Section 116.005(e).