Okla. Stat. tit. 62, § 62-544: Apportionment of interest

On or before the last day of each month the State Treasurer and

the treasurer of each county, city, town and board of education

shall apportion and place to the credit of the sinking fund or

sinking funds in his custody all interest earned and collected from

the investment of such sinking funds, as provided in the first and

foregoing section of this act; provided, that in counties, where

invested securities have heretofore been purchased for the joint use

and benefit of the several school districts and/or townships

thereof, the amount so credited to each such sinking fund account

shall bear the same ratio to the whole amount of interest so

collected, as the amount of such investment credited to the sinking

fund account of each such school district and/or township bears to

the total amount so invested, in which last event the apportionment

of such interest earnings shall be made immediately prior to the

30th day of June of each year.