Subject to the approval of the Compensation Board, the council of any city may enter into contracts with officers providing for salaries for the maximum amount allowed in § 17.1-287 and for the city’s pro rata part of the expense of the office approved by the State Compensation Board, in lieu of fees and commissions prescribed by law for services performed for the city and such contracts may relieve the officer from collecting such fees and commissions. In the event such contract is entered into and approved by the Compensation Board, the officer and the city shall not be liable to the Commonwealth for the failure of such officer to collect fees and commissions prescribed by law for services rendered the city. A copy of every such contract, certified by the clerk of the city council, shall be filed with the Comptroller.