Tax Guide Form 1120: Simplify Your Corporate Tax Returns Form 1120: for calculating corporate annual income tax liability Continuing PDFfiller‘s review of corporate and business tax forms, we turn to IRS Form 1120 for corporations. What is IRS Form ... Tax Guide Form 1120S Schedule K-1: S-Corporation Shareholder Profits Continuing the conversation from last week about tax forms for corporations, there’s another type of Schedule K-1, for S Corporations. The tax return for an S corporation is the ...