Preparatory or auxiliary — meaning in cross-border tax

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A working meaning for Preparatory or auxiliary, written for the return rather than for the textbook.

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Definition

The carve-out that keeps genuinely supporting activity from creating a permanent establishment. It is narrow, and it is tested on what is actually done.

Why the term matters

Structural terms describe how two systems classify the same entity or instrument. Where they disagree, the mismatch — not the rate — is the exposure, and anti-hybrid rules now neutralise the outcome rather than leaving it available.

The team reviewing a file together at a desk

What one system calls it and the other does not

A translated term is not the same term. Where a concept arrives through a treaty or a foreign statute in another language, the working definition is the one in the governing text, and the familiar word in the other language is a label rather than a rule.

Where it turns up

These pages are where Preparatory or auxiliary stops being terminology and starts changing a number.

What to do next

A term like this is worth ten minutes of reading and then a conversation. The reading tells you the question; the conversation answers it. One call now is worth more than a filing season of guessing.

Where a concept appears in a treaty, the governing words are the ones in the treaty in force for your year, not the general description here. Protocols and multilateral positions change them more often than people expect.

Checked and signed off for the 2025 and 2026 filing seasons by Udit Gupta, Cross-Border Tax Expert, Legal Quotient Consultants. General guidance only. Your own facts decide the answer, so bring them to a call before relying on this.

Where international tax accountant comes into this file

Read this page for international tax accountant. It works through preparatory or auxiliary from the beginning — whether it applies to you at all, what has to be filed if it does, and what the engagement costs, priced up front.

Cross-border tax case studies

Case study 1

Liaison office whose staff had begun negotiating terms

The office had been opened to gather market information and pass enquiries to the parent. Over time its manager had started agreeing discounts and delivery dates, with the contract signed abroad afterwards. We examined calendars, the approval trail and several years of customer correspondence, and concluded the carve-out was no longer available. The engagement produced a documented position, registration and filings in the source state from the period the conduct changed, and a revised authority schedule so the boundary is visible to the people who have to stay inside it.

Case study 2

Fulfilment warehouse central to the business it supported

The client held stock in a leased facility and described it as storage and delivery only. Its business was selling goods to local customers on short delivery promises, so the facility was not supporting an activity carried on elsewhere — it was the activity. We set out why the carve-out did not apply, identified the functions performed at the site, and moved the enterprise onto a filing footing there. The work produced a written analysis, a first source-state return, and an attribution basis for the profit those functions earned.

Case study 3

Group companies sharing an address assessed together

A parent ran a procurement function at an address where its subsidiary ran after-sales support, each arguing that its own slice was supporting work. We tested the activities as a combined operation rather than separately, because the enterprises were closely related and the functions were complementary parts of the same business. On that reading the place was not auxiliary to anything. The engagement produced a single written position covering both companies, a filing for the entity whose functions the profit followed, and a note of what would have to change for the earlier view to hold.

Case study 4

Purchasing office that had taken on after-sales work

Purchasing for the enterprise had been the office's only function for years and had been treated as inside the carve-out. Staff had since begun handling warranty claims and customer complaints for the region. We separated the two functions in the record, established when the second began, and assessed the office on what it did as a whole rather than on its original purpose. The result was a dated change of position, filings from that date, and a reorganisation of reporting lines so the functions are no longer indistinguishable in the office's own records.

Case study 5

Defending the carve-out during a source-state examination

An authority had asserted that a client's technical support office was a permanent establishment and had proposed an assessment. The office's activity was genuinely supporting, but nothing had been written down. We assembled the evidence file — job descriptions, board delegations, signing limits, the escalation trail showing every pricing decision taken abroad — and responded with a function-by-function analysis. The examination closed without an assessment, and the client now holds a standing record of the same evidence for each year the office operates.

Case study 6

Setting the boundary before a support hub opened

The client planned a regional hub to handle scheduling and reporting for teams working in several countries. We worked through which functions could sit there without turning the hub into a permanent establishment and which could not, then wrote the boundary into job descriptions, authority limits and the intra-group agreement. The engagement produced a documented pre-opening position, a short annual routine for evidencing what the hub actually did that year, and a list of the changes that would require the position to be revisited.

Case study 7

Three Countries in One File and Two Treaties That Disagree

Income sourced in one country, paid to a resident of a second, held through an entity in a third: three bilateral treaties, no three-way rule. The analysis works out which pair governs each flow, and whether the middle entity is entitled to anything at all.

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Case study 8

An Adjustment in One Country and No Relief in the Other

A pricing adjustment taxes the same profit twice unless the other country makes a corresponding one. The mutual agreement route is what produces that relief, and it is opened on a timetable set by the treaty rather than by either revenue authority.

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Questions that come up on Preparatory or auxiliary

Does a warehouse abroad create a permanent establishment?

It depends entirely on what the warehouse does for that business. Keeping a stock of goods purely for storage, display or delivery has historically fallen inside the carve-out, because it supports a business carried on elsewhere. Where the warehouse is the business — a distribution model whose whole proposition is holding stock close to customers and getting it to them quickly — it is not supporting anything, it is the activity itself, and the carve-out does not apply. The test is the activity's function within that enterprise's own business, so two identical buildings can reach opposite answers.

Is a liaison or representative office preparatory or auxiliary?

Often it is, and often what the staff actually do has drifted from what the office was opened to do. A genuine representative office that gathers information, receives enquiries and passes them to the principal is a strong case for the carve-out. Staff who negotiate price, agree delivery terms or settle the substance of a deal before it is signed elsewhere are doing something else. The label on the office, the intra-group services agreement and the registration under which it was opened do not decide the question; the emails, calendars and authority limits do.

What documents prove our office only does support work?

The useful evidence is contemporaneous and specific to what the people there do: job descriptions that match the actual roles, written limits on signing and pricing authority, the approval trail showing where decisions were taken, correspondence with customers, and the office's own reporting lines. A description of the office drafted for the purpose of the file carries much less weight than records made in the ordinary course. Because the carve-out is tested on what is actually done, and done period by period, the evidence has to be capable of being produced for each year rather than assembled once when a question arrives.

Can we split activities between group companies to stay exempt?

This is specifically anticipated. Where closely related enterprises carry on complementary functions at the same place, or a single enterprise divides its own activity into slices that each look supporting, the activities can be looked at together rather than one at a time. Assessed as a whole, the combined operation is often a cohesive business rather than support for one carried on elsewhere. The practical effect is that a group cannot establish its position by examining each company's activity in isolation, and a structure built on that reading tends to fail at the first examination.

Our office is auxiliary, so can we still have a PE?

Yes. The carve-out answers one question only: whether a fixed place of business creates a permanent establishment. A separate rule looks at people. Someone who habitually plays the principal role in bringing about the conclusion of contracts in the enterprise's name can create a permanent establishment whatever the status of the premises they sit in. So an office can be genuinely supporting and the enterprise still have a permanent establishment through the activity of a person there, or of an agent acting for it. The two questions are answered separately and both have to be answered.

Who has to prove the activity is auxiliary?

Formally that depends on the procedure of the country asking, but in practice the enterprise claiming the carve-out is the party holding the facts and it is the one asked to explain them. An authority can see the premises, the staff and the local costs; the argument that the activity supports a business carried on elsewhere can only be made from the enterprise's own records. That is why the position is better settled and documented while the activity is running, rather than reconstructed from memory years later when the people involved have moved on.

Do I have to file in both countries?

Frequently yes, and the two filings do different jobs. The country where the income arises taxes it at source; the country where you are resident taxes your worldwide income and then gives credit for the tax already paid. Filing only one side is what leaves relief unclaimed — the credit has to be asked for on a return. We prepare both sides so the numbers agree. See dual filing.

How do I actually stop being taxed twice?

In this order. Fix your residence under each country's own rules, and if both claim you, apply the treaty tie-breaker. Identify where each type of income is sourced. Read the article that covers that income type, because it decides who taxes and at what maximum rate. Then claim the relief on the residence-country return, with proof of the foreign tax. Most of the tax people lose to double taxation is lost at the last step, not the first. See how double taxation is relieved.

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