Alabama Income Tax Forms & Instructions. The most common Alabama income tax form is the AL – Form 40. This form is used by Alabama residents who file anCombine these totals with investment income and expenses from all other sources to determine the amount to enter on form FTB 3526, line 1. Line 20c – Other 2018. Instructions for Form 1120. U.S. Corporation Income Tax Return. Department of the Treasury Part III, line 20c. Alabama, Alaska, Arizona,. Forms Archive - Alabama Department of Revenue. Alabama Business Privilege Tax Initial Privilege Tax Return Instruction, 2022. Form CPT with Calculations. Combine these totals with investment income and expenses from all other sources to determine the amount to enter on form FTB 3526, line 1. Line 20c – Other