Ala. Code § 11-50-412
All property and all income of any district incorporated under this article and any such district itself shall be exempt from all state, county, municipal and other taxation in the State of Alabama, including, without limitation, privilege and license taxation. All bonds of such district and the interest thereon shall be exempt from all state, county, municipal and other taxation in the State of Alabama. All deeds, mortgages, indentures of trust and other documents executed by or delivered to any such district shall be exempt from all state, county and municipal and other taxation in the State of Alabama; provided, that these exemptions shall not be retroactive in effect and shall not affect any taxes currently in existence nor any tax previously assessed whether collected or not; provided further, that as of September 1, 1965, the provisions of this section shall not affect or be applicable to any existing contracts, bonds, supporting taxes or existing exemptions, nor shall it affect or be applicable to the refunding of any gas district corporations incorporated of a debt existing on September 1, 1965, taxes or tax assessments and any municipality or county may continue in the future to levy and collect any tax now levied, the passage of this section notwithstanding.
Ala. Code § 11-50-412 (1975)