US Tax Filing Requirements for International Founders – Your Guide

There are certain requirements you have to comply with when filing US tax for your business. Learn what these are so you stay on the right side of the law.

Taxes and IRS filing requirements can be extremely confusing. So we’ve put together an overview of the required filings + key deadlines to keep in mind to stay on top of taxes for your business!

And if you need help filing your paperwork/taxes with the IRS, doola’s Tax Filing services will take the load off your shoulders.

I Am a US Single Owner/Sole Proprietor (Us Single Member LLC) With a Personal Income Tax Filing Requirement

Included Filings:

• Preparation of individual tax return (Form 1040)

• Preparation of one self-employment income form (Schedule C)

• Preparation of one rental real estate property (Schedule E)

• Inclusion of income from one brokerage account (Schedule B/ Schedule D)

Key Dates:

• April 15, 2026: Individual tax returns (Form 1040) including LLCs filing on Schedule C must be filed or to request a six-month extension of time to file.

• October 15, 2026: Final extension deadline (if Form 4868 was filed by June 15) and the official FBAR deadline for expats.

Tip: Filing early helps avoid last-minute stress and delays. If you need more time, file by June 16 or request an extension until October 15.

I Am a Foreign Single Owner/Sole Proprietor (Foreign Single Member LLC)

If you own a Foreign Single Member LLC, and you are not considered as “Engaged in US Trade or Business” you are not required to file 1040NR or pay personal income taxes.

As a “Non-Resident Alien” (aka foreigner), you are only required to file and pay taxes in the U.S if you have FDAP income for which withholding was not done at source, or have effectively connected income (US sourced income) with US Trade or Business.

Here is an extensive article on what may constitute US Trade or Business: **https://oandgaccounting.com/amazon-foreign-sellers-irs-taxes-and-1099-k-reporting/**

However, as of 2017, you still report information like a corporation (see Section 1.6038A-1). Therefore, unless you have registered as a corporation, all single-member LLCs are subject to these requirements. Failure to file or incorrect filling will incur a minimum penalty of $25,000.

Included Filings:

• Preparation of Pro-forma (Form 1120)

• Preparation of foreign owner report (Form 5472)

Key Dates:

• April 15, 2026: Deadline for LLC tax returns when filing as Foreign Owned Disregarded Entity (Forms 1120 and 5472) or to request a six-month extension of time to file.

• April 15, 2026: Deadline to file individual tax returns for foreign individuals (Form 1040NR) or to request an extension for an extra six months to file your return.

Multiple Member LLC

As a “Non-Resident Alien” (aka foreigner), you are only required to file and pay taxes in the U.S if you have FDAP income for which withholding was not done at source, or have effectively connected income (US sourced income) with US Trade or Business.

Here is an extensive article on what may constitute US Trade or Business: **https://oandgaccounting.com/amazon-foreign-sellers-irs-taxes-and-1099-k-reporting/**

I Am a Non-US Multi Owner With US Sourced Income

Included Filings:

• Preparation of partnership return (Form 1065)

• Preparation of one rental real estate investment (Form 8825)

• Preparation of Schedule K-1, K-2 & K-3s for up to four members

• Preparation of forms 8804, 8805 and 8813 may be required if the partnership has effectively connected income with US Trade or Business

• 1040NR is required, and an ITIN will be needed to do the 1040NR

Key Dates:

• March 16, 2026: Deadline for partnership and LLCs owned by multiple members to file tax returns (Form 1065) or to request a six-month extension of time to file.

I Am a Non-US Multi Owner without US Sourced Income

Included Filings:

• Preparation of partnership return (Form 1065)

• Preparation of one rental real estate investment (Form 8825)

• Preparation of Schedule K-1, K-2 & K-3s for up to four members

• Preparation of forms 8804, 8805 and 8813 may be required if the partnership has effectively connected income with US Trade or Business

• No 1040NR required, if all activities reported on the K1, K2, and K3 are foreign sourced or non-US Sourced

Key Dates:

• March 16, 2026: Deadline for partnership and LLCs owned by multiple members to file tax returns (Form 1065) or to request a six-month extension of time to file.

I Am a US Multi Owner (With International Item of Relevance)

International items of relevance is when either a foreign partner involved, or foreign source income is involved.

Included Filings:

• Preparation of partnership return (Form 1065)

• Preparation of one rental real estate investment (Form 8825)

• Preparation of Schedule K-1, K-2 & K-3s for up to four members

• Preparation of forms 8804, 8805 and 8813 may be required if the partnership has effectively connected income with US Trade or Business

• Individual tax return is filed (Form 1040)

Key Dates:

• March 16, 2026: Deadline for partnership and LLCs owned by multiple members to file tax returns (Form 1065) or to request a six-month extension of time to file.

I Am a US Multi Owner (Without International Item of Relevance)

International items of relevance is when either a foreign partner involved, or foreign source income is involved.

Included Filings:

• Preparation of partnership return (Form 1065)

• Preparation of one rental real estate investment (Form 8825)

• Preparation of Schedule K-1, K-2 & K-3s for up to four members

• Preparation of forms 8804, 8805 and 8813 may be required if the partnership has effectively connected income with US Trade or Business

• Individual tax return is filed (Form 1040)

Key Dates:

• March 16, 2026: Deadline for partnership and LLCs owned by multiple members to file tax returns (Form 1065) or to request a six-month extension of time to file.

I Have an LLC That Has Elected to File Taxes as a C-Corporation

Click here to simplify your bookkeeping and taxes with a 30-day free trial

Included Filings:

• Preparation of Corporate Tax Return (Form 1120)

• Preparation of foreign owner report/ Related Party Disclosures (Form 5472)

Key Dates:

• April 15, 2026: Deadline for Corporations or to request a six-month extension of time to file.

I Have a Delaware C Corp (Foreign Owned)

Foreign Owned = a member of the C Corp owns 25% or more of the C Corp

Included Filings:

• Preparation of Corporate Tax Return (Form 1120)

• Preparation of foreign owner report/ Related Party Disclosures (Form 5472)

• DE Corporate Franchise Tax Return (Owners pay required taxes directly)

Key Dates:

• March 1st (DE Franchise Tax Return)

• April 15, 2026: Deadline for Corporations or to request a six-month extension of time to file.

I Have a Delaware C Corp (Domestic)

Included Filings:

• Preparation of Corporate Tax Return (Form 1120)

• DE Corporate Franchise Tax Return (Owners pay required taxes directly)

Key Dates:

• April 15, 2026: Deadline for Corporations or to request a six-month extension of time to file.

• March 1st (DE Franchise Tax Return)

I Have a DAO LLC

Included Filings:

• Preparation of partnership return (Form 1065)

• Preparation of one rental real estate investment (Form 8825)

• Preparation of Schedule K-1, K-2 & K-3s for up to four members

• Preparation of forms 8804, 8805 and 8813 may be required if the partnership has effectively connected income with US Trade or Business

Key Dates:

• March 16, 2026: Deadline for partnership and LLCs owned by multiple members to file tax returns (Form 1065) or to request a six-month extension of time to file.

What Are the Key Dates to Be Aware of in 2025?

Here are the updated tax deadlines for the year 2025:

January 15, 2025:

• Fourth Quarter 2024 Estimated Tax Payment Due:​ Individual filers must pay their fourth-quarter estimated tax payment for the 2024 tax year.​

January 31, 2025:

• Deadline for Employers and Payers:​ Employers must furnish W-2 forms to employees. Payers must send out 1099 forms for interest, dividends, and non-employee compensation to recipients.​

March 17, 2025:

• S Corporation and Partnership Tax Returns Due:​ Deadline for S corporations to file Form 1120S and partnerships to file Form 1065 for the 2024 tax year or to request a six-month extension.​

April 15, 2025:

• Individual Tax Returns Due:​ Deadline to file individual income tax returns (Form 1040) for the 2024 tax year or to request an extension.​

• First Quarter 2025 Estimated Tax Payment Due:​ Estimated tax payments for the first quarter of 2025 are due.

• C Corporation Tax Returns Due:​ Deadline for C corporations to file income tax returns (Form 1120) for the 2024 tax year or to request an extension.​

June 16, 2025:

• Second Quarter 2025 Estimated Tax Payment Due:​ Estimated tax payments for the second quarter of 2025 are due.​

September 15, 2025:

• Third Quarter 2025 Estimated Tax Payment Due:​ Estimated tax payments for the third quarter of 2025 are due.​

• Extended Deadline for S Corporations and Partnerships:​ If an extension was filed, S corporation and partnership tax returns are due.​

October 15, 2025:

• Extended Deadline for Individual Tax Returns:​ If an extension was filed, individual income tax returns for 2024 are due.​

• Extended Deadline for C Corporation Tax Returns:​ If an extension was filed, C corporation tax returns are due.​

January 15, 2026:

• Fourth Quarter 2025 Estimated Tax Payment Due:​ Individual filers must pay their fourth-quarter estimated tax payment for the 2025 tax year.​

📌 Please note that if a due date falls on a weekend or federal holiday, the deadline is typically extended to the next business day. It’s advisable to consult the IRS or a tax professional for the most current and personalized information.​

Save Yourself the Hassle – doola Can Help

That was a lot to take in. And even though the IRS provides information online to fill these forms out on your own, it can be confusing to understand this information and time consuming to fill these forms out.‍

If you need help filing your paperwork/taxes with the IRS, doola offers Tax Filing services where our tax professionals will help you stay ahead of the tax season stress!

That way, you can focus on what you do best: building your business. We’ll handle the rest.