Ala. Code § 40-23-8: Cash Sales and Credit Collections to Be Reported.

Any person taxable under this division, having cash and credit sales, may report such cash sales, and the taxpayer shall thereafter include in each monthly report all credit collections made during the month preceding, and shall pay the taxes due thereon at the time of filing such report, but in no event shall the gross proceeds of credit sales be included in the measure of the tax to be paid until collections of such credit sales shall have been made.