Ala. Code § 37-1-81

(a) Whenever a utility desires to put in operation a new rate or service regulation or to change any existing rate or service regulation, it shall file with the commission a new schedule embodying the same, not less than 30 days prior to the time it desires to make the same effective; but the commission may, upon application of the utility, prescribe a less time within which the same may be made effective. In the absence of suspension or disapproval by the commission, as herein provided, the new rate or service regulation embodied in any such new schedule shall become effective at the time specified in such schedule, subject however to the power of the commission at any time thereafter to take any action respecting the same authorized by this title.

(b) To enable it to make such investigation as, in its opinion, the public interest requires, the commission, in its discretion, for a period not exceeding six months may suspend the operation of any new schedule of rates or service regulations filed with the commission. Unless as a result of its investigation the commission otherwise orders before the termination of such period of six months, such rate or service regulation shall thereupon become effective. The commission may make any order in the premises which it is authorized by any of the provisions of this title to make in any investigation or complaint or on its own motion without complaint.