Ala. Code § 40-18-3
The salaries, fees, commissions or other income of officers or agents of the United States or its agencies and instrumentalities or its contractees, received from the United States or from its agencies and instrumentalities, shall be subject to income taxes levied by the State of Alabama as other income is taxed, but without discrimination, and only to the same extent and in the same manner as other income is taxed, insofar as the State of Alabama may be constitutionally or legally authorized to tax such income; provided, that money paid by the United States to a person as compensation for active service as a member of the armed forces of the United States in a combat zone designated by executive order of the President of the United States shall not be subject to income taxes levied by the State of Alabama for the calendar year 1965 or any subsequent year.
Ala. Code § 40-18-3 (1975)