US Business Entity Types and Tax Forms: Which Return Each One Files

The legal form you choose and the tax form you file are two different things, and mixing them up is the most common planning error we see. This guide to US business entity types and tax forms shows which federal return each structure files for tax year 2025 and what changes when an owner lives in India or Canada. It does not replace the legal advice a lawyer gives on liability or ownership, and state and local taxes are covered separately.

What are the main US business entity types and tax forms?

The IRS groups federal treatment into five structures: sole proprietorships, partnerships, corporations, S corporations and limited liability companies. An LLC is created under state law, and the IRS says it may be classified as a partnership, a corporation or an entity disregarded as separate from its owner.

How is each structure taxed?

Sole proprietor. You report profit or loss on Schedule C, pay self-employment tax on Schedule SE, and make estimated payments on Form 1040-ES. Self-employment tax applies once net earnings reach $400. If you have employees you also file employment tax returns, covered in our employer checklist.

Partnership. The partnership files Form 1065 and gives each partner a Schedule K-1. It pays no income tax itself. Partners are not employees and do not receive Form W-2.

C corporation. The corporation is a separate taxpayer and files Form 1120. The federal rate is a flat 21% of taxable income under the Form 1120 instructions. Profit is taxed again when paid out as dividends, which is why the IRS calls it double tax. A C corporation that files 10 or more returns of any kind in a year must e-file its Form 1120.

S corporation. An S corporation passes income, losses and credits to shareholders, who report them on Form 1040. The corporation must be domestic, have no more than 100 shareholders and one class of stock, and have only allowed shareholders: individuals, certain trusts and estates. Partnerships, corporations and nonresident alien shareholders are not allowed.

How does an LLC choose its tax treatment?

An LLC is an "eligible entity", so it can pick its classification. Without an election, a domestic LLC with one owner is disregarded and one with two or more owners is a partnership. To change that:

1. Corporation or partnership election. File Form 8832. The effective date cannot be more than 75 days before you file or more than 12 months after, and once an entity makes an election you generally cannot change it again for 60 months.
2. S corporation election. File Form 2553 no more than 2 months and 15 days after the start of the tax year the election takes effect. An eligible LLC that files a valid Form 2553 is treated as a corporation without a separate Form 8832.
3. Check the shareholders first. A foreign individual owner makes the S election unavailable.

If you are weighing LLC against corporation under Illinois law, read our Illinois LLC vs corporation guide.

What are the due dates?

The extension applies to filing, not to paying any tax due. See the federal tax calendar for the full year.

How are foreign entities classified in the US?

The check-the-box rules apply to foreign entities as well. Form 8832 lists foreign entities that are always treated as corporations, including a Canadian "Corporation and Company" and an Indian "Public Limited Company". An Indian private limited company or LLP is not on that list, so it is an eligible entity. Under the foreign default rule, an entity whose members all have limited liability is an association taxable as a corporation unless it elects otherwise.

For a foreign parent with a US subsidiary, the classification of both companies matters; our subsidiary reporting guide and foreign-owned LLC guide go further.

A worked example

Karthik lives in Hyderabad and Dana lives in Batavia. They each own half of a new Illinois LLC that expects US$120,000 of profit after expenses. All figures here are hypothetical and ignore Illinois tax and owner salaries.

• Default partnership. The LLC files Form 1065 and issues two K-1s. Karthik's US$60,000 share is effectively connected income, so the partnership withholds on it and Karthik files a US nonresident return. Dana pays income tax and self-employment tax on her share.
• S election. Not available, because Karthik is a nonresident alien.
• C corporation election. Federal tax is 21% x US$120,000 = US$25,200. If the remaining US$94,800 is paid out, Karthik's half is US$47,400. Under the US-India treaty the dividend rate for an individual is 25%, or US$11,850 withheld, against a 30% statutory rate. Dana pays US tax on her dividend.

The right answer depends on what the owners do with the cash, and on how India taxes the same income; we compare the three with your Chartered Accountant.

Mistakes to avoid

• Filing Form 2553 for a company that already has a nonresident alien shareholder or an ineligible owner.
• Assuming an LLC "is" a partnership or a corporation without checking its owners and any election.
• Missing the 75-day look-back and 12-month look-forward limits on Form 8832.
• Treating a foreign-owned disregarded LLC as exempt from filing; Form 5472 still applies.
• Forgetting that states can classify an entity differently from the IRS.

How we can help

We recommend the structure after looking at who the owners are, where they pay tax and how profits will leave the business. We prepare the federal returns for the US side and coordinate with your Canadian CPA or Indian Chartered Accountant so the filings agree. If you are in the Aurora area, we can also line up the Illinois registrations. See business tax returns and planning, business formation and registrations and cross-border tax for India, Canada and the USA. This is general information, not legal advice.

Frequently asked questions

General information only. It is not tax, legal, accounting or immigration advice for your situation, and rules change; confirm the current rules with the official source or a licensed professional in the relevant country.