Income Tax Return for an S Corporation is a tax document used to report the income, losses, and dividends of S corporation shareholders. Section 2 — Information About Corporate Income. If, after you read through this article, you are overwhelmed, start looking for a tax preparer to help you with your business taxes. Schedule L may also be used for organizations in conjunction with Form The Corporate Income Tax Rate. Key Takeaways Schedule L is a form attached to U. Most business expenses are tax-deductible as legitimate business expenses, but each deduction has limits and exclusions, and these change with laws and regulations.