The next question was whether the group would be taxed twice
Why a defensible UK attribution does not by itself secure foreign relief – and why the treaty, taxable-base bridge and MAP timetable must be designed before the returns are filed
Angelo Chirulli ADIT FCA BFP IFA TEP CPA | September 2026
In my previous article, I considered an international group that had accepted an intentional UK permanent establishment and then built the functional ledger, tax balance sheet and four-way reconciliation needed to calculate its profit consistently.
The group had moved beyond registration. It could identify the UK functions performed for the overseas principal, distinguish them from the UK subsidiary’s own activities, attribute the relevant assets and risks, recognise internal dealings and calculate a reproducible UK PE profit.
The board assumed that the principal uncertainty had therefore been resolved.
Finance then asked the question that exposed the next problem: if the United Kingdom taxes that profit, will the overseas company’s state of residence give full relief for the UK Corporation Tax?
The answer was not contained in the UK PE computation.
It was not automatically yes merely because a double tax treaty existed.
And it was not necessarily a simple credit equal to the UK tax paid.
The group had built a defensible source-state attribution. It had not yet demonstrated that the residence state would recognise the same PE, the same amount of profit, the same period or the same tax as eligible for relief.
The relief assumption was not a relief analysis
The first draft tax provision treated the UK Corporation Tax as fully creditable against the overseas principal’s domestic tax. The amount was entered as a line in the consolidation spreadsheet. No separate analysis supported it.
That shortcut contained at least four assumptions:
the applicable treaty required the residence state to relieve the UK tax;
the residence state regarded the UK as entitled to tax the amount attributed to the PE;
the UK tax was imposed on the same taxpayer and the same income included in the residence-state computation; and
the residence-state credit limitation, timing rules and documentary requirements allowed the full amount to be used in that period.
Each assumption required a separate answer. A treaty allocates taxing rights and obliges a state to eliminate qualifying double taxation. It does not make every foreign tax payment automatically creditable, nor does it remove the need to apply the residence state’s domestic machinery for exemption or credit relief.
The treaty had to be read from both ends
The group had initially read only the permanent-establishment and business-profits provisions. Those articles addressed whether the United Kingdom could tax and how much profit could be attributed to the UK PE. They did not complete the relief analysis.
The team also had to examine the elimination-of-double-taxation article, usually based on Article 23 of the OECD Model, together with any protocol, later instrument, reservation and domestic implementing rules. The method could be exemption, credit, or a combination that differed by category of income. The applicable treaty text, rather than a generic model, controlled the outcome.
HMRC’s own guidance makes the source-state point clearly: treaty provisions take precedence where they restrict UK domestic taxing rights, and the treaty business-profits article governs the amount properly attributable to the PE. The residence state must then apply its own treaty obligation and domestic relief mechanism to that same underlying profit.
Source: HMRC International Manual – Article 7 and the interaction between treaty and domestic PE rules
This created a two-sided test. The United Kingdom had to be entitled to tax the profit under Article 7. The residence state then had to determine the relief due under the treaty’s relief article. If the residence state considered that the UK attribution exceeded the amount permitted by Article 7, it might refuse relief for the excess. At that point the issue was no longer a routine credit calculation. It was a treaty dispute.
One economic profit produced three tax computations
The group’s commercial model produced one stream of operating profit, but the tax analysis did not produce one universal measure of that profit.
At minimum, the group needed to reconcile:
the commercial profit attributed to the UK activities under the functional analysis;
the UK taxable profit of the overseas company’s PE after UK tax adjustments; and
the residence-state measure of the foreign company’s income, including the amount treated there as attributable to the UK PE.
Those amounts could differ without either jurisdiction making an arithmetical error. The two tax systems might apply different rules to depreciation and capital allowances, provisions, employee costs, financing expenses, foreign exchange, losses, research expenditure, bad debts or the timing of revenue recognition. They might also use different accounting periods or currency translation conventions.
The computational principle is illustrated by HMRC’s guidance for the mirror-image case of a UK company with a foreign branch. That guidance distinguishes the branch’s commercial profit, the foreign tax measure and the UK tax measure. Credit is limited by the domestic tax attributable to the domestic measure of the same foreign-source profit, not by a notional tax on whichever measure is highest. Other residence states apply their own rules, but the structural point is universal: the same business profit must be mapped across two different tax bases.
Source: HMRC International Manual – branch profits and the matching of commercial and taxable measures
The UK subsidiary tax was not the principal’s foreign tax
The group also had to separate juridical double taxation from economic double taxation.
The UK PE was part of the overseas principal. UK Corporation Tax on the PE profit was tax imposed on that foreign company. Subject to the treaty and the residence state’s domestic rules, that was the tax potentially eligible for exemption or credit at principal level.
The UK subsidiary was a different taxpayer. Its Corporation Tax arose on its own arm’s-length remuneration. That tax did not become creditable to the overseas principal merely because the subsidiary’s employees also performed activities relevant to the PE. Nor could the group net the subsidiary’s profit against the PE profit simply to arrive at an aggregate UK result.
This distinction mattered because the group faced two connected but different risks. First, the same overseas principal profit could be taxed in the United Kingdom and again in the residence state. That was a juridical double-tax issue for the business-profits and relief articles. Secondly, inconsistent pricing between the UK subsidiary and the foreign principal could tax overlapping value in different legal entities. That might require a corresponding adjustment under the associated-enterprises article, domestic relief or MAP.
A single line described as foreign tax credit could not resolve both problems.
The group built a taxable base bridge
The practical solution was a taxable-base bridge that started with the functional attribution and ended with the relief actually available in the residence state. The bridge was not merely a reconciliation of headline profit. It tracked each material adjustment by character, period, currency and legal taxpayer.
| Layer | Core question | Required evidence |
| Commercial attribution | What profit follows the UK functions, assets and risks | Functional analysis, customer and product data, dealings schedule and PE tax balance sheet |
| UK taxable measure | What part of that profit is chargeable under UK law and the treaty | UK tax computation, loss position, capital and interest analysis, payment record |
| Residence state measure | How the same underlying items enter the principal’s domestic tax base | Residence return, domestic adjustments, currency and period mapping |
| Treaty relief | What amount is exempt or creditable and what limits apply | Treaty article, domestic claim, tax certificate, credit limitation and carry rules |
| Residual exposure | What remains taxed twice or deferred after relief | Issue log, protective claims, appeal position and MAP timetable |
The bridge forced the group to identify whether an apparent mismatch was permanent, temporary or merely presentational. A disallowed expense in one country could create a permanent restriction. A different depreciation profile might create a timing difference. An exchange-rate movement could alter the credit cap even where both authorities agreed on the functional attribution.
The distinction mattered for provisioning and decision-making. A temporary cash-tax mismatch required a funding and claims timetable. A permanent denial of relief required technical challenge, operating-model change or dispute resolution.
Timing and currency could create double tax without any treaty disagreement
The UK PE prepared its computation by reference to the overseas company’s accounting period. The residence-state return, however, recognised certain adjustments when tax became final or paid. The foreign tax credit could therefore arise later than the UK liability, even though both jurisdictions ultimately accepted the same PE profit.
The group also prepared management accounts in one currency, UK filings in sterling and residence-state filings in another functional currency. The conversion date for the PE profit did not necessarily match the conversion date for the UK tax. A full sterling credit shown in the UK schedule could become a smaller domestic-currency credit when the residence-state rules were applied.
Losses created a further complication. If the overseas company had no residence-state tax on the relevant profit because domestic losses sheltered it, the credit capacity for that period could be nil or restricted. Whether unused foreign tax could be carried forward, carried back or surrendered depended on local law. The existence of a tax treaty did not answer that domestic utilisation question.
For forecasting purposes, the group therefore separated the effective tax rate from the cash-tax profile. It modelled UK payment dates, residence-state inclusion, credit recognition, loss utilisation, currency translation and any period in which double tax would remain funded pending relief.
A credit claim could not resolve a treaty disagreement
The residence-state adviser initially proposed claiming relief for the UK tax and dealing with any challenge later. That was appropriate only to the extent that the disagreement concerned mechanics or evidence.
If the residence authority denied relief because it considered that no UK PE existed, or that the UK had attributed too much profit to it, a larger credit claim did not cure the underlying issue. The two states were applying the treaty inconsistently. The group needed to preserve domestic appeal rights while considering competent-authority assistance under the Mutual Agreement Procedure.
HMRC describes MAP as available where the actions of one or both tax administrations result, or are likely to result, in taxation not in accordance with the relevant treaty. HMRC will consider whether the issue can be resolved unilaterally and, if not, may discuss it with the other competent authority. Relief is not automatic: the authorities must reach an agreed treaty outcome, and arbitration depends on the applicable convention or instrument.
Source: HMRC Statement of Practice 1 2018 – Mutual Agreement Procedure
MAP was a protective process rather than a last minute remedy
The group did not wait for both assessments to become final before considering MAP. It identified the first notification capable of triggering the treaty time limit, recorded the relevant domestic appeal deadlines and checked which competent authority could receive the request.
That discipline was necessary because MAP time limits do not necessarily follow ordinary return-amendment or appeal periods. HMRC’s published practice notes a UK domestic presentation period of six years after the end of the chargeable period, subject to a longer treaty period, while many modern treaties use three years from the first notification of action resulting or likely to result in taxation contrary to the treaty. The precise convention had to be checked; the group could not manage the timetable by reference to a generic three-year assumption.
The MAP file used the same factual narrative as the PE attribution and the UK subsidiary’s transfer-pricing analysis. It contained the legal structure, relevant treaty text, chronology, computations in both tax systems, evidence of the UK tax, explanation of the disputed amount, domestic proceedings and the relief requested. Inconsistent descriptions of the same decision-makers or risks would have undermined the case before either authority considered the numbers.
For a high-value recurring arrangement, the group also considered whether an advance agreement would be proportionate. HMRC’s APA programme is intended to agree a methodology for complex transfer-pricing issues in advance and to prevent disputes that might otherwise require MAP. The availability and scope of a bilateral solution still depend on the facts and on the other jurisdiction’s process.
Source: HMRC International Manual – Advance Pricing Agreements
The 2026 UK changes increased the need for coordination
For accounting periods beginning on or after 1 January 2026, the UK’s reform package aligns the domestic PE rules more closely with the latest international consensus and introduces a mechanism under which a UK-resident company may claim relief where a transfer-pricing adjustment to a connected foreign company relates to a UK PE.
That mechanism can be important where the foreign principal and UK subsidiary positions overlap. It does not, however, replace the residence state’s obligation to eliminate juridical double taxation of the foreign principal, and it does not convert the subsidiary and PE into one taxpayer. The UK domestic relief, the PE attribution, the subsidiary’s arm’s-length remuneration and the foreign principal’s treaty relief remain separate calculations that must reconcile.
Source: HMRC policy paper – reform of transfer pricing, permanent establishment and Diverted Profits Tax
The four way reconciliation became a filing control
In the earlier stage, the group had reconciled the overseas company’s accounts, the UK PE tax accounts, the UK subsidiary’s result and the residence-jurisdiction treatment. The double-tax review turned that reconciliation into a controlled filing process.
Before either return was filed, tax and finance signed off:
the treaty relied upon and the relief method required in the residence state;
the UK PE profit attribution and UK tax adjustments;
the residence-state mapping of the same income, expenses, assets and internal dealings;
the separation of the UK subsidiary’s remuneration and tax from the principal’s PE tax;
the foreign-tax-credit or exemption computation, including limitations, timing and currency translation;
the evidence that the UK tax had been assessed, paid or otherwise qualified for relief;
the treatment of losses and any unused or deferred relief; and
the deadline and factual trigger for any protective appeal or MAP request.
The group also created trigger events requiring the relief analysis to be revisited. These included a UK enquiry adjustment, a residence-state denial of credit, a change from credit to exemption treatment, a material change in the PE’s capital attribution, a transfer-pricing adjustment affecting the subsidiary, a mismatch in accounting periods, or the expiry of a treaty or domestic deadline.
This meant that foreign relief was no longer added after the UK return had been prepared. It was designed alongside the attribution and monitored as part of the same governance framework.
The group replaced assumed relief with an evidenced position
The first tax provision assumed that every pound of UK Corporation Tax would reduce residence-state tax by one pound.
The completed analysis reached a more qualified conclusion. Most of the UK tax was expected to be relieved. Part of the amount was subject to timing differences. A smaller element exceeded the current-period credit capacity and required separate carry-forward analysis. One disputed attribution item was preserved for competent-authority discussion if the residence authority rejected it.
The effective tax rate was therefore higher than the original spreadsheet suggested.
The cash-tax exposure was also more volatile.
But the position was defensible, documented and manageable.
The board could see which amount represented permanent double taxation, which amount was a timing difference, which relief depended on further evidence and which issue could become a treaty dispute. Finance could forecast the funding requirement. The tax team could protect the relevant time limits before an authority’s final decision made relief more difficult.
The group had not guaranteed that two tax systems would produce identical answers. No taxpayer can do that unilaterally. It had built the process required to identify the differences early and use the treaty machinery before they became embedded in closed periods.
The next question for international groups
A defensible PE profit attribution answers how much the source state may tax. It does not, on its own, answer how double taxation will be eliminated.
A sustainable cross-border filing position must therefore answer six connected questions:
Does the applicable treaty permit the United Kingdom to tax the attributed PE profit?
Does the residence state apply exemption, credit or another relief method to that category of profit?
Are both states measuring the same taxpayer, income and period?
How do differences in tax base, losses, timing and currency affect the relief actually usable?
Has the UK subsidiary’s separate transfer-pricing position been reconciled without treating its tax as the principal’s tax?
If the authorities disagree, have domestic rights and MAP deadlines been protected?
The correct time to answer those questions is when the PE attribution model is designed, not after the UK tax has been paid and the residence-state return has been rejected.
Double-tax relief should be an output of a reconciled treaty and computational analysis. It should never be a balancing figure in the consolidation spreadsheet.
How Vectigalis AC Tax can assist
Vectigalis AC Tax advises UK and international groups on permanent establishments, profit attribution, transfer pricing, treaty relief, Mutual Agreement Procedure, CFCs and cross-border operating-model design.
We can assist with:
coordinated UK PE attribution and residence-state relief reviews;
taxable-base bridges covering commercial profit, UK taxable profit and the residence-state measure;
foreign-tax-credit and exemption analysis, including limitations, losses, timing and currency;
reconciliation of PE profit with UK subsidiary remuneration and the 2026 UK relief mechanism;
MAP readiness reviews, protective filing strategy and competent-authority submissions; and
practical governance, evidence packs and year-end controls for recurring PE positions.
If your group has accepted or identified a UK PE, the foreign-relief position should be reviewed before the UK and residence-state returns are finalised. A technically correct UK attribution can still produce avoidable double tax if the treaty claim, tax-base reconciliation and procedural timetable are addressed only after filing.
Vectigalis AC Tax can undertake a focused PE and double-tax-relief review, identify permanent and timing mismatches, and design a coordinated filing and dispute-resolution framework across the relevant jurisdictions.
Angelo Chirulli FCA ADIT TEP
UK Chartered Accountant and Italian Dottore Commercialista
Vectigalis AC Tax | www.vectigalistax.co.uk | angelo@vectigalistax.co.uk
This article is for general information and does not constitute tax, legal or accounting advice. The outcome depends on the specific facts, the applicable treaty, the jurisdictions involved and the way in which the operating model and relief claims are implemented in practice.
Vectigalis AC Tax | UK and International Tax Advisory