(a) In the various counties of the State of Alabama having a population of less than 600,000 inhabitants according to the last or any subsequent federal decennial census, any tax collector, tax assessor, revenue commissioner, license commissioner, or other elected or appointed official charged with the assessment or collection, or both, of ad valorem taxes in any county of the State of Alabama:

(1) Who has served for 14 years as such an official in any county of Alabama and who has become permanently and totally disabled, proof of disability being made by certificate of three reputable physicians; or

(2) Who has served for 12 years as a county official for any county of Alabama, at least 10 years or more continuously as tax collector, tax assessor, license commissioner, revenue commissioner, or other elected or appointed official charged with the assessment or collection, or both, of ad valorem taxes, and who is not less than age 60;

May elect to become a supernumerary tax collector, tax assessor, revenue commissioner, license commissioner, or other elected or appointed official charged with the assessment or collection, or both, of ad valorem taxes of the county in which the official serves by filing a written declaration to that effect with the Governor. If the Governor finds any declarant qualified either under subdivision (1) or (2) of this subsection, a commission as supernumerary tax collector, tax assessor, revenue commissioner, license commissioner, or other elected or appointed official charged with the assessment or collection, or both, of ad valorem taxes for the county in which the official has served shall be issued to the declarant by the Governor. In computing length of service, the time served as any other county-wide elected official or the time served as chief clerk of the tax collector, tax assessor, license commissioner of any county, shall be counted.

(b) In the various counties of the State of Alabama having a population of less than 600,000 inhabitants according to the last or any subsequent federal decennial census, any person who has served 18 years as a county official for any county of Alabama, the last six or more years as tax collector, tax assessor, revenue commissioner, license commissioner, or other elected or appointed official charged with the assessment or collection, or both, of ad valorem taxes, and previously at least 12 years as chief clerk to the tax collector, tax assessor, revenue commissioner, license commissioner, or other elected or appointed official charged with the assessment or collection, or both, of ad valorem taxes, or previously at least 12 years as a county commissioner, who is not less than age 60 or who has become permanently and totally disabled, proof of that disability being made by certificate of three reputable physicians, may elect to become a supernumerary tax collector, tax assessor, revenue commissioner, license commissioner, or other elected or appointed official charged with the assessment or collection of taxes, or both, by filing a written declaration to that effect with the Governor. If the Governor finds that any declarant is qualified under this subdivision, a commission as supernumerary tax collector, tax assessor, revenue commissioner, license commissioner, or other elected or appointed official charged with the assessment or collection, or both, of ad valorem taxes, for the county in which the official has served shall be issued to the declarant.