US Company Formation from Luxembourg (2026): Soparfi Subsidiaries, the 50% Dividend Exemption, Anti-Hybrid Rules, the US–Luxembourg Treaty's LOB and US LLC vs C-Corp

Luxembourg sits at the centre of a great deal of US investment. Its holding companies (Soparfis), funds and financing vehicles own US businesses and US real estate worth hundreds of billions of dollars. That world runs on specialist advisers. This guide is for a different group: Luxembourg residents and Luxembourg companies with an operating business who want a US company of their own, whether a consultant in Kirchberg with American clients, a fintech in Belval expanding to New York, or a family business opening a US sales office.

The key points for them are the participation exemption, which makes a Delaware corporation the natural subsidiary for a Luxembourg company; the anti-hybrid rules, which make a US LLC owned from Luxembourg more complicated than it looks; and the US–Luxembourg treaty's strict limitation on benefits. This guide covers each and compares US LLC formation with US C-Corp formation.

In short: Luxembourg residents and companies can own 100% of a US LLC or C-Corporation, formed remotely. A Luxembourg company pays an aggregate 23.87% corporate tax in Luxembourg City (16% CIT from 2025, plus solidarity surcharge and municipal business tax). A Delaware corporation owned by a Luxembourg S.à r.l. or Soparfi fits the participation exemption, and the US–Luxembourg treaty cuts US withholding on its dividends to 5%. A disregarded US LLC creates hybrid-mismatch questions under the ATAD rules, and for individuals it may not qualify for the 50% dividend exemption. Interest and royalties from the USA are generally 0% under the treaty, subject to its LOB. With UCB, a Delaware corporation with EIN is $358 and a Wyoming LLC with EIN is $249, all-in.

Luxembourg's rules in brief

• Corporate income tax fell to 16% from 2025 (lower for small profits). With the solidarity surcharge and the municipal business tax of Luxembourg City, the aggregate rate is 23.87%.
• Net wealth tax of 0.5% applies to companies' net assets each year, with exemptions for qualifying participations.
• Personal income tax reaches 42%, plus the solidarity surcharge, for a top marginal rate of about 45.8%.
• Dividends received by individuals from fully taxable Luxembourg companies, from EU companies covered by the Parent-Subsidiary Directive, and from companies resident in treaty countries that are subject to a tax comparable to Luxembourg corporate tax, are 50% exempt.
• Participation exemption: dividends and gains of a Luxembourg company from a holding of at least 10% (or a cost of at least €1.2 million for dividends, €6 million for gains), held for 12 months, in a company subject to comparable tax, are exempt.

Why the corporation fits and the LLC complicates

The Delaware corporation

A Delaware C-Corporation is a taxable company in the USA, paying 21% federal tax plus state tax. For Luxembourg purposes:

• it is clearly opaque, so there is no hybrid mismatch;
• it is subject to comparable tax, so dividends to a Luxembourg company can qualify for the participation exemption, and dividends to an individual for the 50% exemption;
• under the treaty, its dividends to a Luxembourg company owning 10% or more carry 5% US withholding.

The single-member LLC

The IRS disregards a single-member LLC. Luxembourg classifies foreign entities by comparing them with Luxembourg forms, and a single-member LLC with limited liability usually looks like an S.à r.l., so Luxembourg tends to treat it as opaque. The mismatch has consequences:

• For an individual owner, distributions from the LLC are dividends from a foreign company that pays no tax of its own. Such a company is not "subject to a comparable tax", so the 50% exemption is unlikely to apply. The full dividend is taxed at progressive rates.
• For a Luxembourg company owner, the participation exemption also requires the subsidiary to be subject to comparable tax, which a disregarded LLC is not. And the ATAD anti-hybrid rules can deny deductions or include income where payments flow through an entity treated differently in the two countries.
• Luxembourg's reverse hybrid rule (in force since 2022) can treat certain Luxembourg-established transparent entities as taxable. It does not apply to US LLCs as such, but it shows how closely Luxembourg now watches classification differences.

A multi-member LLC that has elected to be taxed as a corporation in the USA (check the box) is easier, because both countries then see a company.

The US–Luxembourg treaty

The treaty in force since 2001 (with a 2009 protocol on information exchange) limits US withholding:

The limitation on benefits

Because Luxembourg is a holding location, the treaty's LOB article is among the strictest the USA has. A Luxembourg company qualifies only if it passes a test such as:

• being owned at least 50% by Luxembourg or US residents (or EU/EEA residents under the derivative benefits test), with base erosion limits;
• carrying on an active trade or business in Luxembourg to which the US income is connected;
• being a listed company.

A Soparfi owned by founders resident outside the EU, with no activity in Luxembourg, often fails, and then the US withholds 30%. Before you rely on treaty rates, have your adviser confirm LOB status and give the US company a correct W-8BEN-E (see W-8BEN-E vs W-8BEN explained).

US C-Corp formation from Luxembourg

US tax position

A US corporation pays 21% federal tax on its profits plus state tax, and files Form 1120 and Form 5472 every year (see the 21% corporate tax explained and the C-Corp guide for non-residents).

Example: a Luxembourg fintech's New York subsidiary

Take an illustrative case: a payments software company in Luxembourg, an S.à r.l. owned by its EU-resident founders and employees, wins US bank clients and hires three people in New York.

• It forms a Delaware corporation, registered in New York, which employs the team, signs US contracts and pays US federal and New York taxes on its margin.
• The S.à r.l. licenses its software to the subsidiary. Royalties carry 0% US withholding under the treaty, and the S.à r.l. passes the LOB because it is owned by EU residents and runs an active business in Luxembourg.
• Dividends from the subsidiary carry 5% US withholding and qualify for the participation exemption in Luxembourg.
• Transfer pricing is documented. Luxembourg and the US both scrutinise intra-group royalties.
• Regulation: a Luxembourg payment licence does not cover the USA. The subsidiary takes US regulatory advice before offering financial services.

See US subsidiary for a foreign company and hiring in the USA as a non-resident company.

Start-ups

Luxembourg start-ups raising money from US investors often need a Delaware C-Corporation at the top. A flip of an S.à r.l. into a Delaware structure has Luxembourg tax consequences for founders, so plan it with advice. See raising US investment as a foreign founder.

US LLC formation from Luxembourg

US tax position

A single-member LLC with a non-resident owner pays no US income tax if the owner works from Luxembourg and the LLC has no US office, employees or dependent agents (see effectively connected income explained). It files Form 5472 with a pro forma Form 1120 every year, and the penalty for missing it is $25,000 (see Form 5472 explained).

Example: a consultant in Luxembourg City

These are illustrative figures, not a client case, at €0.92 to the dollar.

Sophie is a regulatory consultant in Luxembourg City who advises US asset managers on EU fund rules, earning US$150,000 (about €138,000) a year as an indépendante. Some clients would like a US vendor.

• As an indépendante, her profit is taxed at progressive rates up to about 45.8%, with social contributions.
• Through a US LLC run from Luxembourg, the LLC is likely treated as an opaque foreign company. If its place of effective management is in Luxembourg, it is a Luxembourg-resident company paying 23.87%. Distributions to her would not get the 50% exemption, because the LLC pays no comparable tax abroad.
• Through a Luxembourg S.à r.l., she gets the 23.87% corporate rate and the 50% exemption on dividends.

She keeps working as an indépendante and invoices her US clients in dollars. A US LLC adds cost and complexity without a tax benefit.

US property

A Luxembourg individual buying US rental property often uses an LLC for liability protection. The rental income is taxed in the USA on a net basis if the owner elects, and the treaty gives the USA the right to tax it. Luxembourg generally exempts foreign real estate income under the treaty with progression. Ask your adviser how the LLC's classification affects this. See real estate investment LLC for foreigners.

Cross-border workers

About half of Luxembourg's workforce commutes from France, Belgium and Germany. A cross-border worker who forms a US company is taxed by their country of residence, not Luxembourg, on the company's income. See the France, Belgium and Germany guides.

Which state

• Delaware for a corporation, subsidiary or start-up.
• New York where the team works.
• Wyoming for an LLC holding US property in some cases, though the property's state matters more.

See best state for non-residents and the state selector.

What it costs

UCB's prices include state fees and the first year of registered agent service:

• Delaware corporation with EIN: $358.
• Wyoming LLC with EIN: $249, or $348 with a US bank account application.

A Delaware corporation costs $578 a year to keep active. A Wyoming LLC costs $121 a year, or $421 with the annual federal return. A US business address with your own suite number is $60 a year. See what a US LLC costs every year.

Documents and banking

For a company owner, an RCS extract (Registre de Commerce et des Sociétés) and a register of beneficial owners (RBE) extract, plus a board or managers' resolution. For an individual, your passport and proof of address. US banks accept Luxembourg-owned companies but ask detailed questions about holding structures and beneficial owners. See US business bank accounts for non-residents.

Mistakes to avoid

• Assuming a Soparfi gets treaty rates without checking the LOB.
• Using a disregarded LLC as a subsidiary of a Luxembourg company without analysing the anti-hybrid rules and the participation exemption.
• Expecting the 50% dividend exemption on distributions from a US LLC that pays no US tax.
• Running a US LLC from Luxembourg and forgetting it may be Luxembourg-resident.
• Missing Form 5472 in a year when no US tax was due.

Frequently asked questions

What is the best US entity for a Luxembourg company's US business? Usually a Delaware corporation. Both countries treat it as a company, dividends carry 5% US withholding, and the participation exemption can apply.

Does a US LLC work for a Luxembourg resident? It can, but Luxembourg usually treats it as an opaque company that pays no comparable tax, which can cost the 50% dividend exemption and raise anti-hybrid questions.

Is there a US–Luxembourg tax treaty? Yes. Dividends 15% (5% for companies owning 10% or more), interest and royalties 0%, subject to a strict limitation on benefits.

Will my Soparfi pass the LOB? It depends on its owners and activity. Holding companies owned by non-EU residents with no Luxembourg business often fail.

Does my US LLC pay US tax? Not if it has no US office, staff or agents. It files Form 5472 and a pro forma 1120 every year.

How UCB can help

We form US corporations and LLCs for Luxembourg owners and companies remotely: the state filing, EIN, registered agent, US business address and bank application. We prepare W-8BEN-E forms once your adviser confirms treaty eligibility, and each year we file the US returns through our US tax filing service. See our formation, EIN and bank account package.

Setting up a US company from Luxembourg? WhatsApp us at +1 315 961 2956 or email enquiries@ucbsolutions.com.