At the expiration of the current term of office of the tax assessor and the office of the tax collector of the county, or if a vacancy occurs in either office, then immediately upon the occurrence of the vacancy, the office of county revenue commissioner shall be established. If the office of county revenue commissioner is established upon the occurrence of a vacancy in either the office of tax assessor or the office of tax collector, the tax assessor or the tax collector, as the case may be, remaining in office shall be the county revenue commissioner for the remainder of the term of office for which he or she was elected. For the purpose of this subpart the words vacancy in the office of the tax assessor or tax collector shall mean when either of the elected officials holding the office of Tax Collector of Lamar County or Tax Assessor of Lamar County, upon September 19, 2001, should die, resign, retire, or fail to seek reelection to such office, provided that, in the event of a vacancy by the means described above other than death, the vacancy shall not accrue until the effective date of resignation or retirement or until the expiration of the term office for which elected, as the case may be. The county revenue commissioner shall be elected at the general election and every six years thereafter and shall serve for a term of office of six years.