Which form is used for filing a Sub Chapter S Corporation's business income tax returns?

A Subchapter S Corporation, often referred to as an S Corporation, is a special type of corporation that meets specific Internal Revenue Code requirements. One of the key benefits of forming an S Corporation is that it allows income, deductions, and credits to pass through to the shareholders, avoiding double taxation typically associated with traditional corporations.

To file income tax returns for an S Corporation, the appropriate form is 1120-S. This form is designed specifically for S Corporations to report income, gains, losses, deductions, and credits, as well as to provide information regarding the shareholders. It's essential for the S Corporation's tax filing and is separate from the forms used by other types of business entities, such as partnerships or standard corporations.

The other forms listed are designated for different business structures. Form 1040 is used for individual income tax returns, form 1120 is for C Corporations, and form 1065 is used for partnerships. Thus, the choice of 1120-S is specifically aligned with the requirements for S Corporations, making it the correct answer.