Ala. Code § 40-23-103 — Sales Tax Levied on Sale Price Less Credit for Trade-In

Where any used automotive vehicle, motorboat, truck trailer, semitrailer, or house trailer is taken in trade or in a series of trades as a credit or part payment on the sale of a new or used automotive vehicle, motorboat, truck trailer, semitrailer, or house trailer, the tax levied in this article shall be paid on the net difference, that is, the price of the new or used vehicle, motorboat, or trailer sold less the credit for the used vehicle, motorboat, or trailer taken in trade.