The Shelby County Commission may provide an annual expense allowance to the circuit clerk in an amount not to exceed twenty thousand dollars ($20,000) per annum. The expense allowance provided by the county com-mission pursuant to this section shall be paid in equal monthly installments from the general fund of the county and shall be in addition to any other salary or other compensation provided by law, but shall be in lieu of any other expense allowance currently paid to the circuit clerk. (Act 2003–167, p. 472, § 1.)