A grantee awarded funds under this part shall calculate the amount of endowment fund income that it may withdraw and spend at a particular time as follows:

(a) On each date that the grantee plans a withdrawal of endowment fund income, the grantee must determine the amount of the income by calculating the value of the fund that exceeds the endowment fund corpus.

(b) If the total value of the endowment fund exceeds the endowment fund corpus, the grantee may withdraw and spend the excess amount, i.e., the endowment fund income, in accordance with § 52i.9.