This is happening because Alabama is one of the few states that allows you to deduct the FICA taxes (which is Social Security and Medicare tax) you paid from your state taxable income.
You could use the amount of FICA tax from your paystubs that you earned while working in Alabama, or allocate the total amount from your W-2 to the proportion of time lived in AL. FICA tax withheld can be found on the W-2 in Box 4 (Social Security tax) plus Box 6 (Medicare tax).
