Ala. Code § 6-10-12
On July 1, 2017, and at the end of each 3-year period thereafter, the State Treasurer shall adjust each dollar amount in this article or, for each adjustment after July 1, 2017, each adjusted amount, by an amount determined by the State Treasurer to reflect the cumulative change in the consumer price index, as published by the United States Department of Labor, or, if that index is no longer published, a generally available comparable index, for the 3-year period ending on the December 31 preceding the adjustment date and rounded to the nearest twenty-five dollars ($25.00). The State Treasurer shall publish the adjusted amounts. The adjusted amounts apply to exemptions claimed on or after April 1 following the adjustment date.
Ala. Code § 6-10-12 (1975)