How to File Business Taxes: Steps by Entity Type

Fact-checked by the LegalGlass editorial team against primary sources · Published Aug 6, 2026 · Last updated Aug 6, 2026

To file business taxes, identify your entity type and file the matching federal return: Schedule C with Form 1040 for a sole proprietor or single-member LLC, Form 1065 for a partnership, Form 1120-S for an S corporation, or Form 1120 for a C corporation. Pay any self-employment tax and reconcile estimated payments, then file by your deadline. The IRS charges no fee to file.

Who Files a Business Tax Return

Almost every business that earns income files an annual federal return; the form depends on how the business is organized. The IRS Business Taxes overview lists five categories of business tax - "income tax, estimated taxes, self-employment tax, employment taxes, [and] excise tax" - and notes that for income tax "the form you use depends on how your business is organized." Sole proprietors and single-member LLCs report on the owner's return; partnerships and corporations file separate entity returns.

Even a business with no profit generally files: a loss still goes on the return and can offset other income. If you had net self-employment earnings of $400 or more, you must also file Schedule SE, per the Self-Employed Individuals Tax Center. Businesses with employees add employment tax filings on top of the income tax return.

The one entity that never files its own income tax return is a default single-member LLC: because it is a disregarded entity, its owner reports everything on Schedule C inside a personal Form 1040. Every other structure - partnership, S corporation, and C corporation - files a separate federal return under its own name and EIN, then either issues K-1s to owners or, for a C corporation, pays its own tax. That distinction, disregarded owner versus separate filer, drives every step that follows.

What You'll Need Before Filing

Before you start the return, assemble records that substantiate every number on it. The IRS says to keep records that "clearly show your income and expenses." Gather:

• Income records - gross receipts, Forms 1099-NEC and 1099-K, invoices, and bank deposits.
• Expense records - receipts, canceled checks, and card statements for deductible costs.
• Cost of goods sold - inventory counts and purchase records, if you sell products.
• Asset records - purchase dates and prices for property you depreciate.
• Vehicle logs - a contemporaneous mileage log if you deduct car or truck expenses.
• Your EIN - required for partnerships, corporations, and any business with employees; see how to get an EIN.
• Prior-year return and estimated-payment records - to carry over figures and credit payments made.

Step-by-Step: How to File Business Taxes

Filing a business return follows the same five steps regardless of entity; only the form changes.

1. Identify your entity's tax classification. Sole proprietor, single-member LLC, partnership, S corporation, or C corporation - this sets your return.
2. Gather income and expense records. Use the checklist above so every line is supported.
3. Complete the matching return. Enter income, deductions, and cost of goods sold; partnerships and S corporations also prepare a Schedule K-1 for each owner.
4. Compute self-employment and estimated tax. Sole proprietors and partners figure self-employment tax on Schedule SE and credit their quarterly payments.
5. File and pay by the deadline. Submit electronically or by mail, pay any balance due, or file for an extension of time to file.

Sole proprietors file everything as one Form 1040; entity filers submit the business return first so owners have their K-1 before completing personal returns.

Which Return Each Entity Files

The return, the owner statement, and the deadline all key off entity type. Match yours in the table, then read our form comparison for detail.

An LLC has no separate form of its own - it files whichever return matches its default status or its election. See single-member LLC and Form 2553 for how classification is set.

Estimated Taxes and Employment Taxes

Business income tax is largely a pay-as-you-go system, so filing the annual return is only part of the job. Per the IRS, owners "generally have to make estimated tax payments if they expect to owe tax of $1,000 or more" for the year ($500 or more for corporations). These quarterly payments cover income and self-employment tax and are credited on the return.

If you have employees, you also handle employment taxes - Social Security and Medicare, federal income tax withholding, and federal unemployment (FUTA) tax - reported on Forms 941 and 940. Certain activities also trigger excise taxes on Form 720. These are separate from the annual income tax return but part of a full-year filing calendar.

Filing Deadlines

Deadlines depend on entity type under 26 U.S. Code § 6072. Pass-through entities that issue K-1s file first. For a calendar-year business, Form 1065 and Form 1120-S are due March 15 (the 15th day of the third month), and Schedule C on Form 1040 and Form 1120 are due April 15 (the 15th day of the fourth month). A fiscal-year filer counts the same third or fourth month from its own year-end. See when business taxes are due for the full calendar including estimated dates.

Penalties for Late Filing and Late Payment

Filing or paying late triggers penalties under 26 U.S. Code § 6651. The IRS failure-to-file penalty is 5% of the unpaid tax for each month or part of a month the return is late, up to 25%. The failure-to-pay penalty is 0.5% of the unpaid tax per month, also capped at 25%, and interest accrues on top.

Partnerships and S corporations face a separate late-filing penalty charged per partner or shareholder for each month the return is late, even when no tax is due, because they are information returns. That is why a late Form 1065 or Form 1120-S is costly regardless of profit. File an extension before the deadline if you cannot finish the return on time.

Extensions and Amended Returns

You can get more time to file, but not more time to pay. Corporations and partnerships file Form 7004 for an automatic six-month extension; sole proprietors file Form 4868 to extend Form 1040. Both extend only the filing deadline - any tax owed is still due at the original date, and the failure-to-pay penalty runs from there.

If you find an error after filing, amend the return. Individuals use Form 1040-X; partnerships and corporations file the amended version of their entity return. Correcting promptly limits interest and penalties on any additional tax.

Recordkeeping After You File

Keep the records that support a filed return for as long as they may be needed. The IRS advises keeping records "as long as needed to prove the income or deductions on a tax return," and keeping employment tax records for at least four years. Retain income, expense, asset, and vehicle records together with a copy of the filed return and proof of payment. Good records also make next year's return faster and protect deductions if the IRS asks. As a practical baseline, many small businesses keep returns and supporting records for at least three years, since that is the general window in which the IRS can assess additional tax on a filed return.

How to Submit: E-File or Mail

You can file a business return electronically or on paper, and the IRS encourages electronic filing for speed and accuracy. Through IRS e-file, sole proprietors file Schedule C inside their Form 1040 using tax software or a preparer, while partnerships and corporations e-file Form 1065, Form 1120-S, or Form 1120. Some entities are required to e-file: partnerships and corporations that meet the IRS electronic-filing thresholds must file electronically rather than on paper.

Whichever method you choose, keep a complete copy of the filed return and proof of any payment. For the underlying reporting rules and examples by business type, the IRS Publication 334, Tax Guide for Small Business, covers sole proprietors and single-member LLCs in detail. If you discover an error after filing, individuals correct it with Form 1040-X, and entities file the amended version of their return.

Related Guides

• Schedule C - the sole-proprietor and SMLLC return, line by line.
• Form 1120 vs. 1120-S vs. 1065 - pick the right entity return.
• Self-employment tax - the 15.3% tax on business net profit.
• Quarterly estimated taxes - pay income and SE tax during the year.
• When are business taxes due? - every deadline by entity.
• Single-member LLC - how a one-owner LLC is taxed.
• Form 2553 explained - electing S-corp status.
• S-corp vs. LLC - the structure decision behind the return.
• LLC vs. S-corp tax - how the choice changes your tax.
• Business tax hub - all returns, schedules, and deadlines.

Frequently Asked Questions

How do I file taxes for a small business?

Identify your entity type, then file the matching return: Schedule C with Form 1040 for a sole proprietor or single-member LLC, Form 1065 for a partnership, Form 1120-S for an S corporation, or Form 1120 for a C corporation. Pay any self-employment and estimated tax and file by your deadline.

Do I need an EIN to file business taxes?

Not always. A sole proprietor or single-member LLC with no employees can file Schedule C using a Social Security number. Partnerships, corporations, and any business with employees need an EIN, which the IRS issues for free on Form SS-4.

How much does it cost to file business taxes?

The IRS charges no fee to file a business income tax return. Costs come only from software or a paid preparer if you use one. Sole proprietors filing Schedule C add it to Form 1040 at no additional IRS cost.

Can I file business and personal taxes together?

It depends on the entity. A sole proprietor or single-member LLC files business income on Schedule C as part of one Form 1040. Partnerships and corporations file a separate entity return, then owners report their K-1 share on their personal return.

What happens if I file business taxes late?

Under 26 U.S. Code § 6651, the failure-to-file penalty is generally 5% of unpaid tax per month up to 25%, and the failure-to-pay penalty is 0.5% per month up to 25%. Partnerships and S corporations also face per-owner late-filing penalties.

When are small business taxes due?

Partnerships and S corporations file by the 15th day of the third month (March 15 for calendar-year filers); sole proprietors and C corporations file by the 15th day of the fourth month (April 15), under 26 U.S. Code § 6072.

Sources

1. IRS - Business Taxes (five tax types; return depends on organization).
2. IRS - Self-Employed Individuals Tax Center (Schedule C, Schedule SE, $400 threshold, Form 1040-ES).
3. IRS - Estimated Taxes ($1,000 individual / $500 corporate thresholds).
4. IRS - Employment Taxes (Social Security/Medicare, withholding, FUTA; Forms 941 and 940).
5. IRS - Recordkeeping (records that show income and expenses; four-year employment-tax retention).
6. IRS - Failure to File Penalty (5% per month, up to 25%).
7. IRS - Failure to Pay Penalty (0.5% per month, up to 25%).
8. IRS - About Form 7004 (automatic 6-month extension for business returns).
9. IRS - About Form 4868 (individual extension for Form 1040).
10. IRS - E-File for Business and Self-Employed Taxpayers.
11. IRS - Publication 334, Tax Guide for Small Business.
12. IRS - About Form 1040-X, Amended U.S. Individual Income Tax Return.
13. Cornell LII - 26 U.S. Code § 6072, Time for filing income tax returns.
14. Cornell LII - 26 U.S. Code § 6651, Failure to file tax return or to pay tax.

LegalGlass provides general information for educational purposes and is not a law firm or a substitute for advice from a licensed attorney or tax professional. This page is information, not advice. Tax forms, deadlines, penalties, and thresholds change; verify current requirements with the IRS before acting.