Ala. Code § 40-19-4
The taxes levied under the provisions of this chapter shall be due and payable in monthly installments on or before the fifteenth day of the month next succeeding the month in which the tax accrues. On or before the fifteenth day of each month, every motor carrier on whom the taxes levied by this chapter are imposed shall render to the Department of Revenue on a form prescribed by the department a true and correct statement showing: The mileage traveled on the highways of this state for the preceding month, or portion thereof and the number, kind, motor number and make of the motor vehicle so operated, together with such other information as the department may demand and require, and, at the time of making such monthly report, such person shall compute the taxes due and shall pay to the Department of Revenue the amount of taxes shown to be due. The Department of Revenue, for good cause, may extend the time for making any return required under the provisions of this chapter, but the time for filing any such return shall not be extended for a period greater than 60 days from the date such return is due to be made.
Ala. Code § 40-19-4 (1975)