What UK Owners of U.S. Companies Must File with the IRS (2026)
Written by Arik Rozen, CPA, MBA | Virginia License #025991 | September 2026
This guide was prepared by Form5472.online, a U.S. CPA firm specializing in IRS compliance for UK and international owners of U.S. companies. We file for LLC owners, partnership members, and corporation shareholders in the UK and more than 40 other countries.
Short Answer
If you live in the UK and own or co-own a U.S. company — whether an LLC, a partnership, or a corporation — you have annual IRS filing obligations. The specific forms depend on your entity type and ownership structure.
The most common situation for UK founders: a single-member LLC triggers Form 5472 + pro-forma Form 1120. A multi-member LLC or partnership triggers Form 1065. A C corporation triggers Form 1120. Nonresident individuals with U.S.-source income file Form 1040-NR.
Missing any of these filings can result in penalties starting at $25,000. The filing obligation exists regardless of whether your company earned income, and regardless of whether you file self-assessment returns with HMRC.
Form5472.online handles all of the filings above — Form 5472, Form 1065, Form 1120, and Form 1040-NR — for UK and international owners, prepared and signed by a U.S.-licensed CPA.
Key Takeaways
UK residents are classified as "nonresident aliens" under U.S. tax law. This status determines which forms you must file with the IRS.
The required forms depend on your entity type: single-member LLC, multi-member LLC/partnership, C corporation, or individual with U.S.-source income.
The UK–US income tax treaty reduces or eliminates U.S. income tax on certain income types — but it does not eliminate information-reporting obligations such as Form 5472.
A UK accountant (ACA, ACCA, or CIMA qualified) cannot sign a U.S. tax return. Only a U.S.-licensed CPA or IRS-enrolled agent can prepare and sign IRS filings.
Filing your HMRC self-assessment does not satisfy any U.S. IRS obligation. The two are entirely separate.
An extension is available for most filings but must be requested before the original deadline. An extension to file is not an extension to pay.
Step 1: Identify Your Entity Type
Your IRS filing requirement depends entirely on how your U.S. company is structured. Here are the most common situations for UK owners:
Your situation | Entity type | Primary IRS form(s) |
You are the sole owner of a U.S. LLC | Single-member LLC (disregarded entity) | Form 5472 + pro-forma Form 1120 |
You co-own a U.S. LLC with one or more partners | Multi-member LLC (partnership) | Form 1065 + Schedule K-1 |
You own shares in a U.S. C corporation | C corporation | Form 1120 (filed by the company) + possibly Form 5472 |
You personally earned U.S.-source income (rent, services, royalties, etc.) | Individual nonresident alien | Form 1040-NR |
Most UK founders running e-commerce, SaaS, or consulting businesses through a U.S. LLC fall into the first category. UK-based startups incorporated as Delaware C corporations for U.S. venture capital fall into the third category.
Single-Member LLC: Form 5472 + Pro-Forma Form 1120
This is the most common filing requirement for UK founders who opened a U.S. LLC as the sole owner — for example, through Wyoming, Delaware, or New Mexico, often using a formation service such as Stripe Atlas, Firstbase, or Northwest.
A single-member LLC owned by a non-U.S. person is classified by the IRS as a foreign-owned domestic disregarded entity. This triggers two forms, filed together as one package:
Form 5472 — Information Return
Reports any transactions between you (the foreign owner) and the LLC: money in, money out, loans, services, registered agent fees paid from your personal account, and any other transfer in either direction. There is no minimum dollar amount — even a single pound transferred is a reportable transaction. If the LLC had no transactions at all, the form is still required — the transaction section is simply left blank.
Pro-Forma Form 1120 — Cover Return
A stripped-down version of the U.S. corporate return, filed solely as a structural requirement to attach Form 5472. The LLC does not owe corporate income tax on this form.
Penalty: $25,000 per form for failure to file, with additional $25,000 penalties for each 30-day period the failure continues after IRS notification. Both forms must be filed together — submitting only one is treated as an incomplete filing.
Deadline: April 15 of the following year (October 15 with a timely Form 7004 extension request).
Zero-activity LLC note: An LLC that was registered but never used — no revenue, no bank account, no clients — still triggers this annual filing requirement for every year the LLC remains legally registered. The obligation ends only when the LLC is properly dissolved with the state and the IRS.
Multi-Member LLC / Partnership: Form 1065
If your U.S. LLC has two or more members — for example, two UK co-founders, or a UK founder and a U.S. partner — it is treated as a partnership for U.S. tax purposes.
The partnership itself files Form 1065 (U.S. Return of Partnership Income). Each partner then receives a Schedule K-1 showing their share of the partnership's income, losses, and deductions.
As a nonresident alien partner, your K-1 income may be subject to U.S. withholding tax if it is effectively connected with a U.S. trade or business. The partnership is generally required to withhold and remit tax on your behalf.
Deadlines:
Partnership books maintained in the U.S.: March 15 of the following year
Partnership books maintained outside the U.S.: June 15 of the following year
With Form 7004 extension: September 15 of the following year
C Corporation: Form 1120 and Form 5472
Some UK founders incorporate as Delaware C corporations — typically to accept U.S. venture capital, or to structure for a future U.S. acquisition or IPO.
A U.S. C corporation files Form 1120 (U.S. Corporation Income Tax Return) annually. If a foreign person owns 25% or more of the corporation's voting stock, the corporation must also file Form 5472 for any reportable transactions with that foreign shareholder.
Deadlines:
Standard: April 15 of the following year
With Form 7004 extension: October 15 of the following year
UK founders who have raised U.S. venture funding and structured as a Delaware C corporation should confirm with their U.S. CPA whether Form 5472 is required in addition to Form 1120. The 25% ownership threshold applies even after dilution from investment rounds.
Individual Nonresident: Form 1040-NR
If you are a UK resident (not a U.S. citizen, not a green card holder) who personally received U.S.-source income — from U.S. real estate, U.S.-based consulting fees, U.S. investment income, or similar — you may be required to file Form 1040-NR (U.S. Nonresident Alien Income Tax Return).
The UK–US income tax treaty may reduce or eliminate the U.S. tax owed on certain types of income. Treaty benefits must be actively claimed on the return — they are not applied automatically.
Deadlines:
If U.S. income tax was withheld at source: April 15
If no U.S. income tax was withheld: June 15
With extension: October 15
Can My UK Accountant File Form 5472?
No. Form 5472 is a U.S. IRS form. Only a U.S.-licensed tax professional — a Certified Public Accountant (CPA) licensed in a U.S. state, or an IRS-enrolled agent with an active PTIN — is authorized to prepare and sign U.S. tax returns.
A UK accountant holding ACA (ICAEW), ACCA, or CIMA qualifications is licensed to practice in the UK. Those credentials are not recognised by the IRS and do not confer authority to sign U.S. tax returns. Some UK accountants partner with U.S. CPAs for cross-border work — but in that arrangement, the U.S. CPA must prepare and sign the actual Form 5472.
When evaluating any service provider, ask: who is the named U.S.-licensed CPA, what is their license number, and can it be independently verified at the relevant U.S. state licensing board?
Does the UK–US Tax Treaty Help?
The UK–US income tax treaty (in force since 1980, updated 2001) reduces or eliminates U.S. withholding tax on dividends, interest, and royalties paid from U.S. sources to UK residents. It also governs how business profits are taxed when a company has a permanent establishment in both countries.
However, the treaty does not reduce, eliminate, or defer the Form 5472 information reporting requirement. Form 5472 is a reporting obligation — not a tax. The treaty has no effect on it. UK founders who assume the treaty exempts them from Form 5472 are incorrect, and this misunderstanding has resulted in significant IRS penalties.
What About HMRC and UK Tax Returns?
Your UK tax obligations — HMRC self-assessment, VAT returns, Corporation Tax for any UK Ltd company — are entirely separate from your U.S. Form 5472 filing requirement. Filing your self-assessment with HMRC does not satisfy the U.S. obligation. Both must be handled independently.
If your U.S. LLC generates income that is remitted to you in the UK, you may also need to report that income on your UK self-assessment return. Your UK accountant can advise on the UK side. Form5472.online handles the U.S. side.
What Happens If You Have Multiple Missed Years?
If your LLC has been active for more than one year and you have never filed Form 5472, you have multiple delinquent filings. The IRS penalty applies per form per year — meaning three missed years potentially means $75,000 in penalties before any escalation applies.
The IRS provides a voluntary disclosure procedure called DIIRSP (Delinquent International Information Return Submission Procedures) for LLC owners who come forward before receiving an IRS notice. Filing under DIIRSP, with a properly drafted Reasonable Cause statement, significantly improves the chance of penalty abatement. The process requires a licensed U.S. CPA to prepare all back-year returns and the Reasonable Cause narrative.
If you have already received an IRS penalty notice, you can still request abatement — but the process is more time-sensitive and requires immediate CPA action.
All Filing Requirements at a Glance
Entity / Situation | Form(s) Required | Standard Deadline | Extension Deadline | Key Penalty |
Single-member LLC (foreign-owned) | Form 5472 + pro-forma 1120 | April 15 | October 15 | $25,000 per form |
Multi-member LLC / partnership | Form 1065 + Schedule K-1 | March 15 (U.S. books) / June 15 (non-U.S. books) | September 15 | $220/month per partner |
U.S. C corporation (25%+ foreign owner) | Form 1120 + Form 5472 | April 15 | October 15 | $25,000 (Form 5472) + late filing penalties on 1120 |
Individual with U.S.-source income | Form 1040-NR | April 15 / June 15 | October 15 | Late filing and late payment penalties |
Verify This Information
IRS Form 5472 instructions
IRS Form 1065 instructions
IRS Form 1040-NR instructions
UK–US Tax Treaty
Preparer credentials
Arik Rozen, CPA — Virginia License #025991 — verifiable at dhp.virginia.gov
UK founder with a U.S. LLC? File Form 5472 with a U.S.-licensed CPA — prepared, reviewed, and filed directly with the IRS. Flat fee, no surprises.
About the AuthorArik Rozen is a licensed U.S. CPA (Virginia License #025991) and the founder of Form5472.online and Tax-USA.net. He prepares and signs IRS filings for UK and international owners of U.S. companies — including Form 5472, Form 1065, Form 1120, and Form 1040-NR — across more than 40 countries. He is not affiliated with HMRC, the IRS, or any government agency.
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