Ala. Code § 11-81-172

The bonds and interest coupons issued under this article are hereby exempted from any and all state, county, municipal and other taxation whatsoever under the laws of the State of Alabama, and it shall be plainly stated on the face of each such bond as follows: “The principal of and interest on this bond are exempted from any and all state, county and municipal and other taxation whatsoever under the laws of the State of Alabama.”