Ala. Code § 45-3A-51.02
The tax levied under this part, except as otherwise provided, shall be due and payable in monthly installments on or before the twentieth day of the month next succeeding the month in which the tax accrues. On or before the twentieth day of each month after June 1, 1996, every person, firm, or corporation on whom the taxes levied by this part are imposed, shall render to the city, on a form prescribed by the city, a true and correct statement showing the gross proceeds of the business for the next preceding month, together with such other information as the city may demand and require, and at the time of making such monthly report the taxpayer shall compute the taxes due and shall pay to the city the amount of taxes shown to be due. The city, for good cause, may extend the time for making any return required under the provisions of this part but the time for filing any such return shall not be extended for a period greater than 30 days from the date such return is due to be made.
Ala. Code § 45-3A-51.02 (1975)