The Compensation Board shall determine (i) how many deputies and assistants, if any, are necessary to the efficient performance of the duties of the office of the officer filing a report required by § 17.1-283, (ii) what should be the compensation of such deputies and assistants, (iii) what allowance, if any, should be made for office expenses and premiums on official bonds, and (iv) the manner in which such compensation should be paid or such allowance made. Each of such officers shall, on or before the first day of November in each year, report to the Board, on official estimate blanks, furnished for such purpose, an estimate in itemized form showing the amount of expenses expected to be incurred in the operation and maintenance of his office for the ensuing year, and all such expenses must be approved in advance by the Board in order to be deductible under § 17.1-284. Nothing in this section shall be construed as prohibiting the Compensation Board from increasing at any time in the year allowances for such expenses as provided in § 15.2-1636.19. The Compensation Board shall report annually to the Governor on the expenses of such office.