IRS Form 1120-S Overview: S Corporation Tax Filing Guide

IRS Form 1120-S is the official tax return required for S corporations, which are unique "pass-through" business entities for tax purposes. Unlike regular corporations, S corporations avoid double taxation by passing income, losses, and deductions directly to shareholders, who report them on their individual tax returns. DoBusinessTax.com helps small business owners and S corporation shareholders navigate this process quickly and accurately.

Filing Form 1120-S correctly ensures compliance with IRS regulations, maximizes deductions, and helps you avoid penalties. Our team of experienced tax professionals provides guidance and resources to simplify S corporation tax filing.

2025 IRS Form 1120-S

Key Aspects of Form 1120-S Tax Filing

  • Pass-through taxation: Income, deductions, and credits of an S corp flow through directly to the shareholders, avoiding double taxation.
  • Schedule K-1 Reporting: Each shareholder receives a Schedule K-1 detailing their share of income, deductions, and credits for inclusion in their personal returns.
  • Reasonable Compensation: Shareholders who work in the company must receive a reasonable salary subject to payroll taxes, while remaining profits can be distributed tax-efficiently.
  • Annual Filing Requirements: Form 1120-S must be filed annually, typically by March 15 for calendar-year S corps. Filing extensions can be requested using Form 7004.
  • State Tax Compliance: Some states require separate filings for S corporations, and state tax treatment may vary from federal rules.
  • Common Mistakes to Avoid: Late filing, incorrect shareholder allocations, and missed deductions are frequent errors that can trigger IRS penalties.

DoBusinessTax.com’s online tax software helps S corporation owners complete Form 1120-S efficiently, with step-by-step guidance, ensuring accurate reporting and maximizing eligible tax deductions and credits.

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Frequently Asked Questions About IRS Form 1120-S

Answers to the most common questions regarding S corporation tax filing and Form 1120-S.

Form 1120-S is the U.S. federal tax return that S corporations file to report income, gains, losses, deductions, and credits. It is essential for maintaining compliance with IRS regulations.
All domestic corporations that elected S corporation status with the IRS are required to file Form 1120-S annually, regardless of income or activity.
The standard filing deadline is March 15 for calendar-year S corporations. Extensions can be requested via Form 7004, providing additional time to file.
Shareholder income, deductions, and credits are reported via Schedule K-1, which each shareholder receives to include in their individual tax returns. This ensures pass-through taxation.
Yes. Most online tax software and professional accountants support e-filing of Form 1120-S, providing faster processing and confirmation from the IRS.
Common errors include late filing, incorrect shareholder allocation, missed deductions, and failing to submit accurate Schedule K-1 forms. DoBusinessTax.com helps prevent these mistakes.
Deductible expenses include salaries, rent, utilities, business expenses, depreciation, and contributions to employee benefit plans. Correct calculation ensures tax efficiency and compliance.
Yes. We use advanced SSL encryption to ensure your information is completely secure during the filing process. Our software is designed to protect sensitive tax data.
Yes. Our software guides you through both simple and complex tax scenarios, including multiple shareholders, itemized deductions, credits, and estimated taxes.
You can start immediately by signing up on DoBusinessTax.com. Our online software will guide you step-by-step to accurately prepare and e-file your Form 1120-S in minutes.

Resources

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1120S Filing Guide Schedule K-1 Instructions
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