Tax Guide IRS Form 1120S: the Tao of the S Corporation Read up on IRS Form 1120S because tax reporting is slightly different for S Corporations! Moving on in our review of corporate tax forms, PDFfiller takes on IRS Form 1120S ... 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 ...