50.515.  County governing body may impose administrative service fee, when, rate — limit on fee in counties of the third classification. — The governing body of any county may, by order of such governing body, impose an administrative service fee on the county park fund or the county road and bridge fund, or any specific purpose capital improvements fund, authorized pursuant to the provisions of section 67.547, 67.550 or 67.700.  Such administrative service fee shall only be imposed to recoup expenditures made from the county general revenue fund to provide administrative services to the county park fund or the county road and bridge fund, or any specific purpose capital improvements fund authorized pursuant to section 67.547, 67.550 or 67.700, including, but limited to, accounting, bookkeeping, legal services, auditing, investment control, fiscal management, and revenue collection.  Any administrative service fee imposed under this section shall be imposed at a rate which will only generate revenue sufficient to recoup actual expenditures made from the general revenue fund of the county to provide administrative services to the fund against which such service fee is imposed, including both direct and indirect expenditures as determined by an independent audit; provided, that no administrative service fee shall exceed three percent of the total budget of the fund on which such fee is imposed, except in any county of the third classification, in which no administrative service fee shall exceed five percent of the total budget of the fund on which such fee is imposed.