What Is the Preparatory or Auxiliary Activities Exception?

The preparatory or auxiliary activities exception lets a foreign company run limited support operations in another country without those operations creating a taxable permanent establishment (PE) there. It sits in Article 5(4) of the OECD Model Tax Convention and appears in most bilateral tax treaties. The exception is narrow, and it got narrower after the OECD’s BEPS Action 7 reforms and again in the 2025 update to the Model Tax Convention.¹ What passed a decade ago may not pass now.

What “Preparatory” and “Auxiliary” Actually Mean

The decisive question is whether the activity at the fixed place of business forms an essential and significant part of the enterprise as a whole.² If it does, the exception fails.

Preparatory activities happen before the real business begins. Scouting a market, setting up local infrastructure, and testing whether demand exists are typical examples. Auxiliary activities support the main enterprise without generating revenue on their own: internal record-keeping, maintaining communications equipment, back-office processes that serve headquarters.

Two conditions run through every version of the rule. First, the activity must be conducted solely for the stated purpose. A warehouse that stores goods and also fills customer orders has moved past sole storage. Second, the activity must stay subordinate to the company’s profit-making operations. A fixed place of business whose general purpose matches the general purpose of the whole enterprise cannot claim the exception.²

Duration matters too. A three-month presence at a temporary location generally lacks the permanence to be a fixed place of business at all. But recurring use of the same location over months or years cuts against the “preparatory” label, because activity that stretches on indefinitely stops looking like groundwork.¹

The Activities Listed in Article 5(4)

Article 5(4) of the OECD Model Tax Convention identifies specific categories that fall below the PE threshold.³ Most bilateral treaties follow the same structure with treaty-specific variations.

Storage, display, and delivery of the company’s own goods. A warehouse or a showroom qualifies, provided the facility does not process sales or fill orders.
Stock kept at another company’s premises for processing (toll manufacturing on materials the foreign company owns).
Purchasing goods or gathering information. A team stationed overseas solely to buy raw materials or research local market conditions fits here, a common setup when a company is evaluating a new market.
Any other activity of a preparatory or auxiliary character. Advertising, supplying information to the enterprise, and scientific research for the enterprise’s own use are frequent examples.²

The word “solely” does real work in each subparagraph. The moment a facility combines a listed activity with one that isn’t on the list, the whole operation risks losing the exception. A warehouse that starts accepting and processing customer returns has taken on a function tied to revenue generation.

When the Same Activity Is Core Business, Not Auxiliary

Whether an activity is preparatory or auxiliary depends on the company’s own business model. The same activity can be auxiliary for one company and core for another.

Take advertising. For a consumer goods manufacturer, a local advertising office is probably auxiliary, because the company’s core business is producing and selling physical products. For a marketing agency, advertising is the service it sells; an advertising office run by an agency cannot claim the exception because the office’s purpose matches the enterprise’s purpose.² The same logic runs through data collection for a data analytics firm, patent servicing for a licensing company, and logistics management for a freight business.

Tax auditors focus on practical indicators. They look at whether local staff can negotiate contract terms or set prices, because that authority puts the activity at the center of profit-making. They review internal financials and employment contracts to see whether the local office bears meaningful business risk or controls significant assets. They ask whether the activity, if removed, would disrupt the company’s ability to earn revenue. If it would, the activity isn’t auxiliary.

Doing Work for Third Parties

There is a less obvious trap. If a fixed place of business performs functions not only for its own company but also for outside enterprises, the exception fails. An in-house advertising team that takes on work for external clients has become an independent revenue source, and the facility is treated as a PE.²

The Anti-Fragmentation Rule

Before the OECD’s Base Erosion and Profit Shifting (BEPS) reforms, companies routinely sliced their supply chains into individually non-taxable pieces. One location stored goods, another handled deliveries, a third managed customer inquiries. Each piece, in isolation, looked auxiliary. Together, they were a fully integrated business.

BEPS Action 7 closed that gap through Article 5(4.1), an anti-fragmentation rule now built into the Multilateral Instrument and the OECD Model Tax Convention.⁴ The exception no longer applies where:

The same company, or a closely related company, carries on business at the same place or another place in the same country;
That other place already constitutes a PE, or the combined activities of the two locations viewed together are not preparatory or auxiliary; and
The activities at the different locations are complementary functions that are part of a cohesive business operation.

The OECD Commentary illustrates the rule with a manufacturer whose subsidiary operates a store selling appliances in a foreign country while the manufacturer separately owns a warehouse in the same country stocking identical items. When a customer buys at the store, employees retrieve the appliance from the manufacturer’s warehouse for delivery. The warehouse’s storage and the subsidiary’s sales are complementary parts of one distribution operation, so the warehouse cannot claim the storage exception.⁵

The practical effect is that companies now have to document the genuine independence of each foreign location: different offices serving different purposes, separate management lines, no dependency on each other to complete a single commercial process.

Remote Workers and Home Offices

Cross-border remote work opened a new PE risk. An employee working from a home office in another country can, in some circumstances, create a taxable presence for the employer. The 2025 update to the OECD Model Tax Convention added specific commentary on this for the first time.¹

Two factors drive the analysis: working time and commercial reasons.

An employee who works from home in a foreign country for less than 50% of total working time over twelve months generally does not create a PE. Crossing 50% doesn’t automatically trigger PE status either; it shifts the analysis to whether the employer has a commercial reason for the employee’s presence in that country. Commercial reasons include meeting local customers, building a new client base, managing local supplier relationships, or delivering services in a particular time zone. Allowing remote work simply to retain an employee or reduce costs is not a commercial reason.

The OECD Commentary works through several scenarios:

An employee working 30% from home with no local clients: the home is used regularly, but the limited time means it is generally not treated as the employer’s place of business. No PE.¹
An employee working 80% from home with regular visits to local clients: PE exists, because the employer has a commercial reason for the presence.
An employee working 60% from home with only sporadic client contact: no PE. The time threshold is crossed, but the presence lacks a genuine commercial purpose.
An employee working nearly 100% from home delivering virtual services across time zones: PE exists, because the employer benefits commercially from having the employee serve customers in that time zone in real time.

Even where a home office creates a PE on these tests, the preparatory or auxiliary exception can still save the employer. An employee working full-time from home on internal administrative tasks may not trigger a taxable presence, because those tasks remain subordinate to the company’s core business.

Websites, Servers, and Digital Activity

The OECD Commentary addresses digital operations directly. A website is a combination of software and electronic data with no physical location, so it cannot by itself constitute a place of business.⁶ A company can host a site accessible to customers worldwide without that site creating a PE anywhere.

Servers are different. A physical server in a data center is tangible equipment at a fixed location, and it can constitute a PE if the company owns or leases it and it stays in place long enough to be fixed.⁶ A server-based PE can exist even with no employees present.

The exception still applies to servers. A server used solely to host an information site, mirror data for backup, or cache content to speed delivery is likely performing auxiliary functions. A server that processes customer orders, collects payments, or delivers the company’s core digital product goes past the exception. The closer the automated functions come to what the company actually sells, the harder it is to call them auxiliary.

What Failing the Exception Costs

Losing the exception does not just mean paying tax in the foreign country. It sets off a chain of filings, calculations, and potential penalties.

Once a PE exists, the host country can tax business profits attributable to it. Under Article 7 of the OECD Model Tax Convention, taxable profits are calculated as if the PE were a separate enterprise dealing at arm’s length with the rest of the company. That requires a transfer pricing analysis, expense allocation (including a share of executive and administrative overhead), and capital attribution that determines how much interest the PE can deduct.⁷ The company also has to file local corporate returns, keep local books, and often register with tax authorities.

U.S. Filings for Companies Claiming the Exception

A foreign corporation that maintains an office or place of business in the United States must file Form 1120-F by the 15th day of the fourth month after year-end. Without a U.S. office, the deadline moves to the 15th day of the sixth month.⁸

A company that argues its U.S. activities do not create a PE because they are preparatory or auxiliary is taking a treaty-based position, which must be disclosed on IRS Form 8833.⁹ The penalty for failing to disclose is $1,000 per failure, or $10,000 for C corporations, and it can be imposed even if the underlying treaty position is correct.¹⁰

Companies confident they have no PE should still consider filing a protective return. It preserves the right to claim deductions and credits against any effectively connected income if the IRS later reclassifies the activities as a PE. Without one, a company can end up paying tax on gross income with no deductions at all, because the right to deductions depends on timely filing. Protective returns are generally treated as timely if filed within 18 months of the original due date.⁸

Penalties, Interest, and How Far Back the IRS Can Go

The IRS accuracy-related penalty is 20% of the underpayment attributable to negligence or substantial understatement.¹¹ For a company that never filed Form 1120-F, a separate failure-to-file penalty runs at 5% per month, up to 25% of unpaid tax; returns filed more than 60 days late trigger a minimum penalty of $525 or 100% of the underpayment, whichever is less.¹²

Interest compounds daily from the original due date. For the first quarter of 2026, the IRS charges 7% on standard corporate underpayments, dropping to 6% in the second quarter. Large corporate underpayments over $100,000 face 9% and 8% for the same periods.¹³ Over several years, compounding interest alone can approach or exceed the underlying tax.

The look-back period is the last piece and often the most damaging. The IRS ordinarily has three years from filing to assess more tax. If the company never filed a U.S. return, there is no statute of limitations, and the IRS can assess for any year no matter how far back. Omitting more than 25% of gross income extends the window to six years, and fraud stops the clock from ever starting. The same unlimited look-back applies where required information returns on foreign entities were never filed; the statute on the underlying income tax return does not start until those information returns are filed.¹⁴ A company that operated for years assuming it had no PE can face the full tax bill for every open year, accuracy and failure-to-file penalties, and years of compounding interest on top.

1
OECD. The 2025 Update to the OECD Model Tax Convention
2
Internal Revenue Service. Preparatory and Auxiliary Treaty Exception to Permanent Establishment Status
3
OECD. Model Tax Convention on Income and on Capital 2017 Full Version
4
OECD. Explanatory Statement to the Multilateral Convention to Implement Tax Treaty Related Measures to Prevent BEPS
5
EY Tax News. OECD Releases Final Report on Preventing the Artificial Avoidance of Permanent Establishment Status Under Action 7
6
OECD. Addressing the Tax Challenges of the Digital Economy Action 1 2015 Final Report
7
OECD. Attribution of Profits to Permanent Establishments
8
Internal Revenue Service. Instructions for Form 1120-F (2025)
9
Internal Revenue Service. Form 8833 Treaty-Based Return Position Disclosure Under Section 6114 or 7701(b)
10
Office of the Law Revision Counsel. 26 USC 6712 Failure to Disclose Treaty-Based Return Positions
11
Internal Revenue Service. Accuracy-Related Penalty
12
Internal Revenue Service. Failure to File Penalty
13
Internal Revenue Service. Quarterly Interest Rates
14
Internal Revenue Service. Overview of Statute of Limitations on the Assessment of Tax