(a) If, at any time, the guardian of the estate has on hand money belonging to the ward in an amount that provides a return that is more than is necessary for the education, support, and maintenance of the ward and others the ward supports, if applicable, the guardian may lend the money for a reasonable interest rate.
(b) The guardian of the estate is considered to have obtained a reasonable interest rate for a loan for purposes of Subsection (a) if the interest rate is at least equal to 120 percent of the applicable short-term, midterm, or long-term interest rate under Section 7520, Internal Revenue Code of 1986, for the month during which the loan was made.