How to file your first business tax return

The first return sets patterns the business will follow for years: its accounting method, how assets are depreciated, how startup costs are treated. This guide explains which form you file, what to prepare, and the decisions that are made for the first time on that return.

By Awais Jameel, Chartered Accountant. Reviewed by Muhammad Bilal, Chartered Accountant. Checked against official sources on . 2 minute read.

Short answer

Your first business tax return depends on how the business is taxed: Schedule C with your Form 1040 for a sole proprietor or single-member LLC, Form 1065 for a partnership, Form 1120-S for an S corporation, and Form 1120 for a C corporation. Close the year's books first, tick the initial return box on entity returns, and make first-year choices such as accounting method and depreciation.

At a glance

Sole proprietor or single-member LLC
Schedule C with Form 1040, due April 15
Partnership or multi-member LLC
Form 1065, due March 15
S corporation
Form 1120-S, due March 15
C corporation
Form 1120, due April 15
Foreign-owned single-member LLC
Form 5472 with a pro forma 1120, due April 15
First-year choices
Accounting method, depreciation, startup costs
How to file your first business tax returnSole proprietor or single-member LLC: Schedule C with Form 1040, due April 15; Partnership or multi-member LLC: Form 1065, due March 15; S corporation: Form 1120-S, due March 15; C corporation: Form 1120, due April 15; Foreign-owned single-member LLC: Form 5472 with a pro forma 1120, due April 15; First-year choices: Accounting method, depreciation, startup costs.KEY FACTS AT A GLANCEHow to file your first business tax returnSole proprietor or single-member LLCSchedule C with Form1040, due April 15Partnership or multi-member LLCForm 1065, due March 15S corporationForm 1120-S, due March 15C corporationForm 1120, due April 15Foreign-owned single-member LLCForm 5472 with a proforma 1120, due April 15First-year choicesAccounting method,depreciation, startupcostsChecked against official sourcesTax BakersHow to file your first business tax returnSole proprietor or single-member LLC: Schedule C with Form 1040, due April 15; Partnership or multi-member LLC: Form 1065, due March 15; S corporation: Form 1120-S, due March 15; C corporation: Form 1120, due April 15; Foreign-owned single-member LLC: Form 5472 with a pro forma 1120, due April 15; First-year choices: Accounting method, depreciation, startup costs.KEY FACTS AT A GLANCEHow to file your first businesstax returnSole proprietor or single-member LLCSchedule C with Form 1040, due April 15Partnership or multi-member LLCForm 1065, due March 15S corporationForm 1120-S, due March 15C corporationForm 1120, due April 15Foreign-owned single-member LLCForm 5472 with a pro forma 1120, due April15First-year choicesAccounting method, depreciation, startupcostsChecked against official sourcesTax Bakers
Key facts at a glance, as set out in this guide.

Which form does your business file?

How the business is taxedFederal returnDue, calendar year
Sole proprietor or single-member LLC, US ownerSchedule C with Form 1040April 15
Single-member LLC, foreign ownerForm 5472 with pro forma Form 1120April 15
Partnership or multi-member LLCForm 1065 and K-1sMarch 15
S corporationForm 1120-S and K-1sMarch 15
C corporationForm 1120April 15

If you are not sure how the business is taxed, see how LLCs are taxed.

What should you gather?

  • A closed set of books for the year: profit and loss account and balance sheet. See the year-end bookkeeping checklist.
  • The formation documents, EIN and any election forms already filed.
  • A list of equipment bought, with dates and costs.
  • Startup and organizational costs incurred before the business opened.
  • Forms 1099 and 1099-K received, and records of estimated tax paid.
  • Owner contributions and withdrawals.

Which decisions are made on the first return?

  • Accounting method. Cash or accrual, adopted by using it on the first return. Changing later generally needs IRS consent. See cash vs accrual accounting.
  • Tax year. Usually the calendar year for small businesses.
  • Depreciation. Whether to expense equipment in full under Section 179 or bonus depreciation, or spread it. See deductible business expenses.
  • Startup and organizational costs. Up to $5,000 of each can generally be deducted in the first year, with the rest spread over 180 months, subject to a phase-out for larger amounts.

Costs from before opening follow special rules. See start-up and organizational costs.

Is anything different about a first return?

Entity returns, such as Forms 1065, 1120-S and 1120, have an initial return box to tick. A business that started part way through the year files for the period from its start date to the end of its tax year, which can be a short year.

What if you need more time?

Businesses file Form 7004 by the original due date for a six-month extension, and individuals file Form 4868. Tax is still due by the original date. See Form 7004 and Form 4868.

What about state returns?

Most states have their own income tax or franchise returns, and some require returns from pass-through businesses. See franchise tax explained.

What should you set up for next year?

Estimated tax payments based on this year's result, a calendar of deadlines, and a monthly bookkeeping routine. See estimated quarterly taxes and US business tax deadlines.

If you find a mistake after filing a personal return, see Form 1040-X.

Want your first return done right?

We close your first year's books, prepare the return with the right first-year elections, and set up next year's estimates and deadlines.

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Questions people ask

Which tax form does my new business file?

Schedule C for a sole proprietor or single-member LLC, Form 1065 for a partnership, Form 1120-S for an S corporation, and Form 1120 for a C corporation.

When is the first business tax return due?

March 15 for partnerships and S corporations, April 15 for sole proprietors and C corporations, for calendar-year businesses.

What decisions are made on a business's first return?

The accounting method, tax year, depreciation choices and the treatment of startup and organizational costs.

Can I deduct startup costs on my first return?

Generally up to $5,000 in the first year, with the rest spread over 180 months, reduced for larger totals.

Sources

Every fee, date and rule on this page was taken from these official and primary sources.

  1. IRS Publication 583: Starting a Business and Keeping Records
  2. IRS Publication 538: Accounting Periods and Methods
  3. Internal Revenue Code sections 195 and 709: startup and organizational costs
  4. IRS: Instructions for Form 1065 (2025)
  5. IRS: Instructions for Form 1120 (2025)

Rules and fees change. If you are reading this long after September 30, 2026, confirm the figures with the source before you rely on them.

Business tax by entity typeHow LLCs are taxed: the four optionsBookkeepingYear-end bookkeeping checklist before you fileDeadlines, penalties and IRS noticesUS business tax deadlines: the full calendar

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This guide is general information. It is not tax or legal advice for your situation.