S corporations generally pass business income, losses, deductions, and credits through to their shareholders rather than paying federal income tax on ordinary business profits.
An S corporation generally must file Form 1120-S each year and provide Schedule K-1 to each shareholder.
S corporation tax treatment can help eligible businesses avoid the double taxation that may apply to C corporations, but it also comes with specific filing, payroll, and shareholder reporting requirements.
The corporation must file its own annual tax return even though most income passes through to shareholders. This generally means filing Form 1120-S and preparing Schedule K-1 for each shareholder. Owners who work for the business may also need to receive reasonable compensation through payroll.
If you operate an S corporation, understanding how to file Form 1120-S, which additional tax forms are required, and when everything is due is important for avoiding penalties and keeping the business compliant.
Key Summary: S Corporation
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S corporations generally use pass-through taxation, with income and losses reported by shareholders on their individual tax returns.
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An S corporation generally must file Form 1120-S each year and issue Schedule K-1 to each shareholder.
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For calendar-year S corporations, the 2025 Form 1120-S was due March 16, 2026, or September 15, 2026 with a timely extension.
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Shareholder-employees who work for the business generally must receive reasonable compensation before taking non-wage distributions.
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Late Form 1120-S filings can result in penalties even when the S corporation does not owe federal income tax.
S Corporation Tax Quick Facts
| Topic | What to Know |
|---|---|
| Main tax return | Form 1120-S |
| Federal tax treatment | Income and losses generally pass through to shareholders |
| Shareholder reporting | Schedule K-1 |
| S corporation election | Form 2553 |
| 2026 filing deadline | March 16, 2026 for calendar-year 2025 returns |
| Extension | Generally six months using Form 7004 |
| Extended deadline | September 15, 2026 for calendar-year corporations |
| Payroll taxes | Generally apply to wages paid to shareholder-employees |
| State taxes | Requirements vary by state |
What is an S Corporation?
An S corporation is a corporation or other eligible business entity that elects to be taxed under Subchapter S of the Internal Revenue Code.
Unlike a C corporation, an S corporation generally does not pay federal income tax on its ordinary business profits. Instead, income, losses, deductions, and credits pass through to shareholders and are reported on their individual tax returns.
S corporation status is a tax classification rather than a type of legal entity, which means an eligible LLC can also elect to be taxed as an S corporation.
Need Help Filing Your S Corporation Taxes?
Make sure your Form 1120-S, Schedule K-1s, and other required filings are prepared correctly and on time. Talk to tax experts today!
How Are S Corporations Taxed?
S corporations are generally treated as pass-through entities for federal income tax purposes. The corporation’s income, losses, deductions, and credits pass through to its shareholders, who report their allocated amounts on their individual tax returns.
For example, if an S corporation has $100,000 of taxable business income and two shareholders each own 50%, each shareholder would generally be allocated $50,000 of the corporation’s income.
Importantly, shareholders may owe tax on their allocated income even if the S corporation does not distribute all of that income in cash.
Certain entity-level federal taxes can still apply in specific circumstances, and S corporations may also have state tax obligations.
What Tax Forms Does an S Corporation File?
The exact forms required depend on the corporation’s activities, employees, and shareholders. However, these are some of the main S corporation tax forms.
Form 1120-S
Form 1120-S, US Income Tax Return for an S Corporation, is the primary federal tax return filed by an S corporation.
It reports the corporation’s income, gains, losses, deductions, credits, and other tax information and determines the amounts that pass through to shareholders.
Schedule K-1
An S corporation generally prepares Schedule K-1 (Form 1120-S) for each shareholder.
The K-1 reports the shareholder’s share of items such as ordinary business income or loss, investment income, capital gains, deductions, and credits. Shareholders use this information when preparing their individual tax returns.
Form 2553
Businesses generally elect S corporation tax treatment by filing Form 2553, Election by a Small Business Corporation.
The election generally must be filed no later than two months and 15 days after the beginning of the tax year in which it is intended to take effect. Late-election relief may be available in certain circumstances.
Form 7004
An S corporation that needs additional time to complete Form 1120-S can generally request an automatic six-month extension using Form 7004.
The extension provides additional time to file, but it does not extend the deadline for any tax that may be due.
S corporations with employees may also have payroll filing requirements, including Forms 941, 940, W-2, and W-3.
How to File Form 1120-S
Filing Form 1120-S involves reporting the corporation’s financial activity and determining how its tax items are allocated among shareholders.
Here is the general process.
1. Gather the Corporation’s Financial Information
Start with complete accounting and tax records for the year, including:
- Business income and expenses
- Payroll and shareholder compensation
- Fixed assets and depreciation
- Shareholder contributions and distributions
- Loans and interest
- Shareholder ownership information
- Prior-year tax returns
Accurate records are important because the amounts reported on Form 1120-S ultimately affect each shareholder’s individual tax return.
2. Report Income and Business Deductions
Report the corporation’s income and allowable business deductions on Form 1120-S.
Common deductions can include salaries and wages, rent, interest, depreciation, taxes and licenses, employee benefits, advertising, and professional fees.
Certain items must be separately stated because their tax treatment can depend on the individual shareholder’s circumstances.
3. Complete Schedule K
Schedule K summarizes the corporation’s income, deductions, credits, and other tax items that pass through to shareholders.
Additional schedules may be required depending on the corporation’s activities. For example, Schedules K-2 and K-3 may apply when the corporation has certain items of international tax relevance.
4. Prepare Schedule K-1 for Each Shareholder
The corporation prepares Schedule K-1 for each shareholder showing their allocated share of the corporation’s tax items.
Shareholders then use their K-1 information to prepare their individual tax returns.
5. Complete Other Required Schedules
Depending on the corporation’s circumstances, Form 1120-S may require additional financial information, including balance sheet and reconciliation schedules such as Schedule L, Schedule M-1, and Schedule M-2.
6. File Form 1120-S by the Deadline
Once completed, Form 1120-S and all required schedules must be filed with the IRS by the applicable deadline.
The corporation must also provide Schedule K-1 to each shareholder so they can complete their individual income tax returns.
Get Your S Corporation Tax Filing Right
From Form 1120-S to shareholder reporting and payroll requirements, our tax professionals can help keep your S corporation compliant.
When is the S Corp Tax Filing Deadline in 2026?
An S corporation generally must file Form 1120-S by the 15th day of the third month after the end of its tax year.
For most calendar-year S corporations, the usual deadline is March 15. Because March 15, 2026 fell on a Sunday, calendar-year S corporations filing their 2025 tax returns had until: March 16, 2026
Fiscal-year S corporations generally file by the 15th day of the third month following the close of their tax year.
What is the S Corp Extension Deadline?
An S corporation that cannot complete its return on time can generally request an automatic six-month extension using Form 7004.
For calendar-year S corporations filing their 2025 returns, a timely extension moved the filing deadline to: September 15, 2026
The extension provides additional time to file Form 1120-S. It does not necessarily provide additional time to pay any entity-level tax that may be due.
S Corporation Owners, Payroll, and Reasonable Compensation
One of the most important S corporation tax rules involves shareholders who also work for the business.
A shareholder-employee who performs services for the corporation generally must receive reasonable compensation as wages before receiving non-wage distributions.
Those wages are generally subject to payroll taxes, including Social Security and Medicare taxes. By contrast, a shareholder’s share of ordinary S corporation business income generally is not treated as self-employment income.
This distinction is one reason some profitable business owners consider S corporation tax treatment. However, owners cannot simply classify all business earnings as distributions to avoid employment taxes.
There is no single salary that qualifies as reasonable compensation for every S corporation. Factors such as the shareholder’s duties, experience, responsibilities, time devoted to the business, and comparable compensation may all be relevant.
S Corporation Late Filing Penalties
An S corporation can face penalties for filing Form 1120-S late even when the corporation does not owe federal income tax.
For returns required to be filed in 2026 where no tax is due, the base late-filing penalty is generally $255 for each month or part of a month the return is late, multiplied by the number of shareholders, for up to 12 months.
For example, if an S corporation with three shareholders files two months late:
$255 × 3 shareholders × 2 months = $1,530
Additional penalties may apply when tax is due or when required shareholder information is not provided correctly and on time.
Penalty relief may be available when the corporation can establish reasonable cause, depending on the circumstances.
Advantages and Disadvantages of an S Corporation
S corporation tax treatment can provide potential tax advantages, but it also comes with additional compliance requirements.
Advantages
- Pass-through taxation: Business income generally passes through to shareholders rather than being subject to regular federal corporate income tax.
- Potential employment tax savings: After reasonable compensation is paid, additional qualifying business income generally is not subject to employment taxes in the same way as wages.
- Avoiding C corporation double taxation: S corporation profits generally are not subject to both corporate income tax and shareholder dividend tax in the same way as C corporation profits distributed as dividends.
Disadvantages
- Additional compliance: S corporations may need payroll, employment tax filings, W-2 reporting, Schedule K-1 reporting, and an annual Form 1120-S.
- Reasonable compensation rules: Shareholder-employees cannot simply classify all business earnings as distributions to avoid employment taxes.
- Ownership restrictions: S corporations generally cannot have more than 100 shareholders, certain types of shareholders are not permitted, and only one class of stock is generally allowed.
- State tax differences: Some states impose separate taxes or filing requirements on S corporations.
Can an LLC Be Taxed as an S Corporation?
Yes. An eligible LLC can elect to be taxed as an S corporation.
An LLC is a legal entity created under state law, while S corporation status is a federal tax classification. A business can therefore remain an LLC for legal purposes while electing S corporation tax treatment.
An eligible LLC generally makes the S corporation election using Form 2553.
Whether the election provides a tax advantage depends on factors such as business profit, reasonable owner compensation, payroll costs, state taxes, and additional compliance expenses.
S Corporations for Americans Living Abroad
Americans living abroad can continue to own S corporations as long as the corporation continues to meet the eligibility requirements. However, moving overseas can introduce additional tax considerations.
Another country may not recognize an S corporation or its pass-through treatment in the same way as the United States. Owners may therefore need to consider foreign tax residency, local taxation of the company, payroll, foreign tax credits, tax treaty provisions, Social Security or totalization rules, and state residency.
Cross-border S corporation owners should consider both the company’s US filing requirements and the tax rules in their country of residence.
