Federal tax liability calculation
C Corporations calculation
For C Corporations, the actual federal tax liability equals the amount on Form 1120, Page 1, Total tax minus the amounts on Form 1120, Page 1, Credit for tax paid on undistributed capital gains and Form 1120, Page 1, Credit for Federal tax on fuels.
S Corporations calculation
For S Corporations, the actual federal tax liability is the amount on Form 1120S, Page 1, line 22c minus the amount for Form 1120S, Page 1, Credit for Federal tax paid on fuels for S Corporations.