Which tax form is used for business income as a corporation?

Form 1120 is the tax form specifically designed for corporations to report their income, deductions, and credits to the Internal Revenue Service (IRS). Corporations, regardless of whether they are C corporations or S corporations, use this form to calculate their tax liability. It provides detailed information about the corporation’s financial activities, allowing the IRS to assess the company's financial health and compliance with tax obligations.

Other forms listed serve different purposes: Form 1040 is for individual income tax returns, Form 1065 is used by partnerships to report income, deductions, and other tax items while Form 990 is intended for exempt organizations, such as non-profits, to report their financial information to the IRS. Each of these fulfills a distinct role in the tax reporting system, reinforcing the importance of using Form 1120 specifically for corporate entities.