Ala. Code § 40-2-44
There is hereby created the office of Assistant Commissioner of Revenue of the Department of Revenue. Such Assistant Commissioner of Revenue shall possess the qualifications and take the oath of office required by law of the Commissioner of Revenue and shall be appointed and hold office under and according to the provisions of the state Merit System as provided now or hereafter by Chapter 26 of Title 36.
The Assistant Commissioner of Revenue shall perform such duties as are assigned to him by the Commissioner of Revenue. In the absence of the Commissioner of Revenue, the Assistant Commissioner of Revenue shall assume the duties of the office of the Commissioner of Revenue. He shall have and exercise in all matters the full authority granted by law to the Commissioner of Revenue if the Commissioner of Revenue shall have delegated such duties and authority to him in writing.
Ala. Code § 40-2-44 (1975)