Cross-Border Tax Scenarios: Payroll, Treaty and Compliance
Context and Challenge
The main challenge with cross-border tax is that employers, executives and advisers routinely underestimate the number of issues that interact. A single overseas working arrangement can trigger payroll withholding, social security obligations, treaty claims, corporate tax exposure, immigration risk and governance failures simultaneously. Common symptoms include: tax and payroll in the wrong country, dual withholding, double tax, social security paid in the wrong place and equity awards vesting across borders without sourcing analysis, and so on. These scenarios illustrate the range of situations and the type of judgement required.
Who Should Read This
HR directors, CFOs, finance directors, payroll managers, reward teams, company secretaries, NEDs, chairs, C-suite executives, directors, founders, recruitment teams, employment lawyers, immigration advisers, tax advisers and relocation professionals dealing with cross-border people arrangements.
Core Finding and Summary
Cross-border people tax issues arise whenever someone works, travels or holds responsibilities across more than one country. Every scenario requires assessment of tax, payroll, treaty, reliefs, social security, pensions, immigration and governance obligations before the arrangement or work begins. These thirty anonymised scenarios cover the most common situations employers and advisers encounter across UK–US, UK–UAE, UK–Switzerland, UK–Germany, UK–Netherlands and multi-jurisdiction corridors.
Decision point: Has the employer identified where duties are performed, where tax is due, which payroll obligations arise, whether treaty relief is available, which social security system applies, Permanent Establishment (PE) risks and whether governance controls are in place?
The Issue
What triggers it?
An employee, director or executive working, travelling or holding responsibilities across borders.
Why does it matter?
Non-compliance creates payroll, tax, social security, immigration, corporate tax and governance exposure.
What decision is needed?
Determine which obligations apply in each jurisdiction and implement controls before the arrangement begins.
Executive Moves and Senior Hires
*Does a UK director working in New York trigger US payroll?
Corridor: UK–US
Situation: A UK-resident director travelled repeatedly to New York to meet investors, advisers and potential US commercial partners while remaining employed and paid exclusively through UK payroll.
The Risk & Opportunity: The employer treated the trips as short-term business travel. US federal, New York State and New York City withholding obligations, shadow payroll requirements, social security certification, treaty relief availability and income sourcing across the travel period all required assessment.
Advisory Approach: Fenton reviewed the director's US workday count and travel, nature of duties performed, remuneration structure, RSU vesting schedule, existing PAYE position and prior adviser input, then coordinated the UK and US analysis to establish whether Federal, NYS or NYC tax and withholding applied. Social Security and other issues like Permanent Establishment risks were also considered.
Commercial Outcome: The employer established a defensible payroll position before the travel pattern became historic, reducing double withholding and late registration risk.
Technical Entities: UK PAYE, US shadow payroll, New York State withholding, New York City tax, Article 15, RSUs, foreign tax credits, PE risk, treaty relief.
*Can a senior executive working from a holiday home in France create corporate tax risk?
Corridor: UK–France
Situation: A senior executive with strategic decision-making authority began working regularly from a holiday home in the south of France while remaining on UK payroll and attending UK board meetings remotely.
The Risk & Opportunity: The executive's overseas presence created potential French corporate tax exposure through permanent establishment, French personal tax and residence risk, social security coordination questions and UK corporate residence concerns if board decisions were being made from France.
Advisory Approach: Fenton assessed the nature and frequency of the executive's French duties, reviewed board minute records and decision-making patterns, coordinated the French and UK personal tax and social security position, and clarified the corporate tax and PE exposure for the employer. Other issues like payroll and expense reporting were also considered.
Commercial Outcome: The employer implemented governance controls and travel limits before the arrangement created an assessable French corporate tax presence.
Technical Entities: Permanent establishment, corporate residence, French personal tax, social security coordination, board decision-making, UK PAYE, governance controls, Article 15, economic employer.
*Does split-year treatment apply when relocating to or from the UK?
Corridor: UK–US
Situation: A senior employee was relocating from the UK to the United States mid-tax year. The employer assumed UK tax would cease on the departure date and US tax would begin on arrival.
The Risk & Opportunity: UK split-year treatment is not automatic. The employee's eligibility depended on meeting specific statutory conditions. If split-year treatment did not apply, the employee would remain UK tax resident for the full year, creating overlapping UK and US tax exposure on worldwide income.
Advisory Approach: Fenton reviewed the employee's ties to the UK, the timing and permanence of the move, the applicable split-year case, and coordinated the interaction between UK departure, US arrival, treaty residence and employer payroll obligations in both countries.
Commercial Outcome: The employer confirmed split-year eligibility before departure, allowing payroll and withholding to be structured correctly from day one.
Technical Entities: Split-year treatment, UK tax residence, statutory residence test, US tax residence, treaty residence, Article 4 tie-breaker, PAYE, US withholding, foreign tax credits.
*Can a senior executive be treaty resident outside the UK while working in the UK?
Corridor: UK–UAE
Situation: A senior executive claimed treaty tax residence in the UAE while continuing to perform some duties in the UK for a UK employer on a regular basis. The individual maintained UK property, family connections and financial ties.
The Risk & Opportunity: Treaty residence requires meeting the conditions of the relevant double tax agreement, not simply holding a UAE residence visa. The individual also needed to fail the UK tax residence test (SRT) to be regarded as not resident in the UK. The treaty residence provisions only apply when someone is regarded as tax resident in both countries under their domestic rules. Article 4 of the treaty will then provide relief by way of a tie breaker so that an individual .
Advisory Approach: Fenton assessed the individual's UK and UAE ties under both the statutory residence test and the UK-UAE double taxation arrangement, reviewed the treaty tie-breaker provisions, and clarified the interaction between treaty residence and UK employment income sourcing.
Commercial Outcome: The employer and individual understood that treaty residence did not automatically eliminate UK payroll or tax reporting obligations for UK-sourced duties. Regardless of residence, the executive was still taxable in the UK on the income relating to the work he did here. Residence determined how he would be taxed eg limited taxation vs worldwide taxation and helped apply to get payroll restricted (not stopped).
Technical Entities: Treaty residence, UK-UAE double taxation arrangement, Article 4 tie-breaker, statutory residence test, UK PAYE, employment income sourcing, NIC, UAE residence visa.
*Can a UK executive move to Switzerland and keep UK benefits?
Corridor: UK–Switzerland
Situation: A UK-based executive was relocating to Zurich on a permanent transfer. The executive wanted to continue participating in the UK pension scheme, retain UK private medical insurance and maintain UK share plan membership after the move.
The Risk & Opportunity: Continued UK benefit participation after a permanent move to Switzerland creates questions about Swiss social security obligations, UK pension tax relief eligibility, the tax treatment of employer-provided benefits in Switzerland, and cantonal tax registration requirements that vary by location.
Advisory Approach: Fenton reviewed the executive's benefit package, assessed the interaction between UK and Swiss pension rules and Swiss social security, clarified the Swiss tax treatment of retained UK benefits by canton, and coordinated with the employer's reward and payroll teams on the transition.
Commercial Outcome: The employer structured the benefit transition before the move, avoiding unexpected Swiss tax charges and preserving the executive's pension position where possible.
Technical Entities: Swiss social security, UK pension tax relief, cantonal tax, Zurich tax registration, employer benefits, PAYE cessation, Certificate of coverage, UK-Switzerland treaty, cross-border pension.
*Does a London-based MD working 80+ days in New York create a US PE?
Corridor: UK–US
Situation: A managing director based and employed in London was spending approximately 80 to 90 working days per year in the New York office, meeting US clients, attending internal leadership meetings and participating in US revenue-generating activities.
The Risk & Opportunity: The volume and nature of the US duties risked creating a US permanent establishment for the UK entity if the individual was negotiating or concluding contracts, or exercising authority on behalf of the UK company while in the United States.
Advisory Approach: Fenton reviewed the individual's US activity log, the nature of duties performed, contract authority, client-facing responsibilities and the interaction between the UK-US treaty PE provisions and US domestic tax rules, then assessed both the personal tax, social security, withholding and corporate tax exposure.
Commercial Outcome: The employer implemented activity limits and contract authority controls before the travel pattern created an assessable US corporate tax presence.
Technical Entities: Permanent establishment, UK-US treaty Article 5, dependent agent PE, US corporate tax, shadow payroll, New York State withholding, contract authority, governance controls.
Employer Payroll and Compliance
*Can a UK employee work remotely from Dubai and stay on UK payroll?
Corridor: UK–UAE
Situation: A UK employee requested to work remotely from Dubai for an extended period while remaining on UK payroll. The UK employer had no UAE entity, no local payroll registration and no prior experience of managing a remote worker in the region.
The Risk & Opportunity: Working from Dubai does not automatically remove UK payroll obligations, but it may create UAE obligations depending on duration, immigration status and local labour law. The employer also needed to assess whether continued UK NIC applied, whether the employee's UK tax status and tax residence was affected, and whether the arrangement created a Permanent Establishment (PE) risk.
Advisory Approach: Fenton assessed the duration and structure of the proposed arrangement, reviewed the interaction between UK tax, residence, PAYE, NIC, UAE labour law, immigration status and corporate tax exposure, and advised on the controls and documentation needed to support the position.
Commercial Outcome: The employer made an informed decision on whether to approve the arrangement, with a clear understanding of the payroll, tax and immigration obligations in both countries. National Insurance continued for upto 52 weeks under these arrangements.
Technical Entities: UK PAYE, NIC, UAE labour law, Dubai immigration, PE risk, statutory residence test, remote working policy, employer of record, social security.
*Can overseas employees visit the UK without triggering UK PAYE?
Corridor: UK inbound
Situation: A UK employer regularly hosted overseas-based employees for meetings, training, client visits and project work in the UK. The employer assumed short visits did not create UK payroll obligations.
The Risk & Opportunity: Depending on the circumstances, UK PAYE obligations can arise from the first day of UK work regardless of visit duration. Treaty relief, HMRC's short-term business visitor arrangements and Appendix 4 agreements may provide relaxation, but they do not apply automatically and require evidence, documentation and employer registration. Employees from countries without a tax treaty with the UK, NIC implications and the filing status and obligations in the home country also need to be considered.
Advisory Approach: Fenton reviewed the employer's inbound visitor patterns, assessed which visits triggered tax, NIC, PAYE and other reporting obligations, identified where treaty relief or STBV arrangements were available, and recommended a tracking and approval process for future visits.
Commercial Outcome: The employer implemented a compliant visitor tracking process and applied available PAYE relaxations where the conditions were met, reducing the risk of historic liabilities. Trailing obligations in the home country were also advised on, together with ways to mitigate Permanent Establishment (PE) risks in the UK.
Technical Entities: UK PAYE, STBV, Appendix 4, treaty relief, Article 15, employer registration, NIC, short-term business visitors, day-count tracking, HMRC reporting.
*How should employers manage payroll withholding in two countries?
Corridor: Multi-country
Situation: An employer had employees working across two countries simultaneously — splitting time between a UK head office and an overseas location — and was uncertain whether payroll should be run in one country or both countries, and was worried about double withholding.
The Risk & Opportunity: Running payroll in the wrong country, or failing to operate a payroll where required, creates withholding failures and potential penalties for the employer and compliance risk in both jurisdictions. The interaction between treaty relief and payroll withholding obligations is not always straightforward. Sometimes it is a requirement to operate payroll in two countries at the same time. There are ways however to often apply to reduce or stop payroll withholdings to improve cash flow for the employee but this is not a unilateral decision taken by an employer. It usually requires certain conditions to be met, and relevant approvals obtained.
Advisory Approach: Fenton reviewed the split of duties, the employment contract structure, the payroll arrangements in each country, the applicable treaty provisions and the social security position, then recommended a payroll structure that met the withholding obligations in both countries while applying available relief. Applications were made to reduce payroll deductions to improve cash flow.
Commercial Outcome: The employer implemented a coordinated dual-country payroll structure that met obligations in both jurisdictions and minimised double withholding for the employee.
Technical Entities: Shadow payroll, modified payroll, dual payroll, PAYE, foreign withholding, treaty relief, Article 15, social security coordination, employer compliance, payroll registration, double withholding.
*Does a UK employer sending a researcher to Germany for four months trigger a shadow payroll?
Corridor: UK–Germany
Situation: A UK life sciences company seconded a clinical researcher to a German facility for four months to oversee a trial. The employee remained on UK payroll throughout. The employer treated the arrangement as a short-term business trip.
The Risk & Opportunity: Germany requires payroll withholding from the first day of work unless treaty relief applies and the employer has confirmed the position with the authorities. A four-month secondment is likely to trigger German wage tax obligations, social security registration and potentially an A1 certificate requirement. Misclassification as a business trip does not remove the obligation.
Advisory Approach: Fenton reviewed the secondment terms, the nature of duties, the German wage tax position, the social security coordination rules, the A1 certificate requirement and the interaction with UK PAYE, then coordinated with the German payroll adviser on registration and withholding.
Commercial Outcome: The employer registered for German wage tax before the secondment began and applied for the A1 certificate, avoiding retrospective payroll correction and penalties. An application was made to reduce to payroll deductions to improve cash flow.
Technical Entities: German wage tax, shadow payroll, A1 certificate, social security coordination, EU regulation, UK PAYE, life sciences secondment, Lohnsteuer, employer registration.
*Can a UK employee stay on UK payroll during an overseas secondment?
Corridor: Multi-country
Situation: A UK employer was seconding an employee to an overseas subsidiary for twelve months and wanted to keep the employee on UK payroll throughout to simplify administration and maintain benefit continuity.
The Risk & Opportunity: Maintaining UK payroll during an overseas secondment does not remove the requirement to operate local payroll withholding in the host country where duties are performed. The employer may need to run shadow payroll, register as an employer in the host country, or coordinate withholding between the two payrolls to avoid double deduction or under-withholding. National Insurance contributions are also likely to continue subject to the relevant rules and agreement between the two countries.
Advisory Approach: Fenton assessed the host country's payroll withholding rules, the treaty position, the social security coordination requirements and the interaction with the UK PAYE position, then recommended a payroll structure that maintained UK continuity while meeting host country obligations.
Commercial Outcome: The employer maintained UK payroll continuity while operating compliant host country withholding, avoiding retrospective correction risk. The NIC and social security position was also aligned and documented.
Technical Entities: Shadow payroll, UK PAYE, host country withholding, social security coordination, A1 certificate, certificate of coverage, NT code, s690, secondment, employer registration, treaty relief, payroll continuity.
Board, Non-Executive Director (NED) and Governance
*Does a non-resident NED of a UK company need UK payroll or pay UK tax?
Corridor: UK inbound
Situation: A non-UK-resident individual was appointed as a non-executive director of a UK company. The NED attended board meetings in the UK, received fees and had travel and accommodation costs paid by the company.
The Risk & Opportunity: Directors' fees paid by a UK company for UK board duties are generally subject to UK PAYE regardless of the director's residence. Travel and accommodation costs for board attendance may also be taxable. The NED's home country may also tax the fees, creating a double taxation issue that requires treaty analysis. National Insurance Contributions and other forms of remuneration such as consulting income or sock options also need to be considered.
Advisory Approach: Fenton reviewed the NED appointment terms, the fee structure, the travel and accommodation arrangements, the UK PAYE position, the NED's home country tax treatment and the applicable treaty provisions for directors' fees, then advised on the tax, payroll, expense reporting and treaty relief position.
Commercial Outcome: The company implemented UK payroll for the NED's fees and applied the correct treaty analysis before the first board meeting, avoiding retrospective PAYE liabilities. The NED paid the correct amount of tax in the UK and at home, and avoided double tax.
Technical Entities: Directors' fees, UK PAYE, NED, Article 16, treaty relief, travel and accommodation, employer NIC, board duties, non-resident director, self-assessment.
*Are director travel and accommodation costs taxable on cross-border board duties?
Corridor: Multi-country
Situation: A UK company paid travel, accommodation and subsistence costs for non-executive directors attending board meetings in London. Several NEDs were resident overseas and claimed these costs were not taxable because the travel was to a temporary workplace.
The Risk & Opportunity: HMRC does not treat a company's board meeting location as a temporary workplace for directors. Travel and accommodation costs paid for board attendance are generally taxable as employment income and potentially subject to PAYE and employer NIC, regardless of the director's residence status.
Advisory Approach: Fenton reviewed the company's NED expense policy, the PAYE treatment of each cost category, the interaction with the directors' home country tax positions and the applicable treaty provisions, then recommended a compliant expense and reporting structure. Fenton also advised on a tax policy in relation to these additional costs.
Commercial Outcome: The company corrected its expense treatment before HMRC inquiry, ensuring all director costs were reported and taxed correctly.
Technical Entities: Directors' expenses, PAYE, employer NIC, temporary workplace, board meetings, Article 16, NED fees, P11D reporting, travel and subsistence, benefit in kind.
*Can a UK-resident director of an overseas company be taxed abroad?
Corridor: UK outbound
Situation: A UK-resident individual held a non-executive directorship with a company incorporated and managed overseas. The individual attended board meetings abroad, received fees from the overseas company and incurred travel costs.
The Risk & Opportunity: Many countries tax directors' fees at source under Article 16 of the applicable treaty, regardless of where the director is resident. The UK-resident director may face foreign tax on the fees, with UK tax also applying on worldwide income. The interaction between foreign withholding, NICs/social security taxes, UK self-assessment and foreign tax credit relief requires coordination.
Advisory Approach: Fenton reviewed the treaty provisions for directors' fees in the relevant country, assessed the foreign withholding position, the UK self-assessment obligations and the availability of foreign tax credit relief, and coordinated the reporting in both jurisdictions.
Commercial Outcome: The director understood the tax cost in both countries before accepting the appointment and structured the fee arrangement to apply available treaty relief.
Technical Entities: Article 16, directors' fees, foreign tax credit, UK self-assessment, overseas board duties, withholding tax, treaty relief, NED fees, double taxation.
Equity, Reward and Pensions
*Are RSUs taxable when an employee relocates mid-vesting?
Corridor: UK–US
Situation: A UK employee holding unvested restricted stock units relocated to the United States before the vesting date. The RSUs were granted while the employee was UK-resident and working exclusively in the UK.
The Risk & Opportunity: RSU income is typically sourced across the jurisdictions where the employee worked during the vesting period. Both the UK and the US may seek to tax a portion of the gain, and the employer may have withholding obligations in both countries. Without sourcing analysis, the employee faces double taxation and the employer faces dual withholding exposure.
Advisory Approach: Fenton assessed the RSU grant terms, the vesting schedule, the employee's work locations during the vesting period, the UK and US sourcing rules, the treaty provisions for employment income and equity, and the employer's withholding obligations in both countries.
Commercial Outcome: The employer applied the correct sourcing split before vesting, operated coordinated withholding in both countries and the employee claimed available foreign tax credit relief. The NIC and social security position was also determined and the correct documentation put in place.
Technical Entities: RSUs, equity sourcing, UK PAYE, US withholding, Section 409A, foreign tax credits, Article 15, vesting period, restricted stock units, employer withholding, NIC-social security.
*Can employees keep contributing to a home-country pension after relocating?
Corridor: Multi-country
Situation: An employee relocating from the UK to an overseas assignment wanted to continue contributing to the UK workplace pension. The employer planned to maintain UK pension contributions throughout the assignment to avoid disrupting retirement planning.
The Risk & Opportunity: Continued UK pension contributions during overseas residence may not qualify for UK tax relief if the employee is no longer UK-resident or no longer has UK-relevant earnings. The host country may also require mandatory pension or social security enrolment. In the absence of treaty relief, employer pension contributions may also be taxable in the host country. The interaction between UK pension rules, treaty provisions where applicable, overseas mandatory pension and social security coordination determines what is permissible.
Advisory Approach: Fenton reviewed the employee's UK tax residence position during the assignment, the UK pension tax relief rules, the host country's mandatory pension requirements, the treaty position, social security coordination position and the employer's obligations under both UK and host country pension legislation.
Commercial Outcome: The employer confirmed which pension contributions remained tax-effective and which required restructuring before the assignment began. Consideration was also given to the employees future plans and where the pension income would be subject to tax on retirement.
Technical Entities: UK pension tax relief, auto-enrolment, overseas pension, social security coordination, A1 certificate, host country mandatory pension, relevant UK earnings, cross-border pension, retirement, treaty.
*How do UK EMI share options interact with US tax when an employee relocates?
Corridor: UK–US
Situation: A UK tech company had granted Enterprise Management Incentive options to several employees. One employee subsequently relocated to the United States before exercising the options.
The Risk & Opportunity: UK EMI options receive favourable UK tax treatment, but the US IRS does not recognise UK EMI status. The employee faces potential US taxation on the option gain under US domestic rules, and the employer may have US withholding obligations at exercise. Without coordination, the employee risks double taxation and the employer risks non-compliance in both countries.
Advisory Approach: Fenton reviewed the EMI option terms, the employee's exercise timeline, the UK and US tax treatment at exercise, the interaction between UK capital gains treatment and US ordinary income treatment, the employer's withholding obligations and the treaty provisions for employment income from equity.
Commercial Outcome: The employer and employee understood the US tax cost (federal and state) before exercise and coordinated the withholding and reporting obligations in both countries. The relocation also had an impact on how the options would be valued in the US for tax purposes, any elections made, timing when tax was due, tax rates, NIC/social security taxes and foreign tax credits.
Technical Entities: EMI options, enterprise management incentives, US Section 83, UK capital gains, foreign tax credits, employer withholding, PAYE, US federal and state tax, equity sourcing, NIC/social security taxes, elections, valuation.
*Does a life sciences executive splitting time between Basel and Cambridge need dual social security?
Corridor: UK–Switzerland
Situation: A senior life sciences executive split working time between the company's Basel research facility and its Cambridge headquarters, spending approximately two/three days per week in each location.
The Risk & Opportunity: Under the UK-Switzerland social security agreement, the applicable social security system depends on the proportion of time worked in each country. If the executive works 25% or more in the country of residence, social security generally applies in the residence country. Incorrect allocation creates dual contribution risk or a gap in social security coverage.
Advisory Approach: Fenton assessed the executive's working pattern, residence position, the applicable UK-Switzerland social security coordination rules, the 25% threshold test, the certificate of coverage requirements and the employer's contribution obligations in both countries.
Commercial Outcome: The employer applied for the correct certificate of coverage and aligned social security contributions with the applicable rules before the arrangement created retrospective exposure.
Technical Entities: Social security coordination, UK-Switzerland agreement, 25% rule, certificate of coverage, A1 equivalent, NIC, Swiss social security, Basel, Cambridge, dual contributions.
*Does the Dutch 30% ruling expiry affect UK-seconded employees?
Corridor: UK–Netherlands
Situation: A UK company had several employees seconded to the Netherlands who benefited from the Dutch 30% ruling, which allows a generous tax-break for qualifying inbound employees. The ruling was approaching its expiry date.
The Risk & Opportunity: When the 30% ruling expires, the employee's Dutch taxable income may increase significantly. The employer's payroll costs may also rise if gross-up or tax equalisation arrangements are in place. If the employee's secondment terms were designed around the ruling, the expiry changes the financial position for both parties.
Advisory Approach: Fenton reviewed the secondment terms, the tax equalisation or tax protection arrangements, the impact of the ruling expiry on Dutch taxable income and employer costs, and the options for restructuring the arrangement including potential localisation or repatriation.
Commercial Outcome: The employer modelled the post-expiry cost impact and restructured the affected assignments before the ruling expired, avoiding unexpected cost escalation.
Technical Entities: Dutch 30% ruling, Netherlands payroll, tax equalisation, tax protection, secondment costs, expat ruling, employer cost, localisation, inbound employee, Dutch wage tax.
Remote Work and Work From Anywhere
*Does an employee working abroad without approval trigger payroll and PE risks?
Corridor: Multi-country
Situation: An employer discovered that several employees had been working from overseas locations for extended periods without formal approval from HR, payroll or tax. The employees had continued to be paid through UK payroll with no assessment of overseas obligations.
The Risk & Opportunity: Unapproved overseas work can trigger host country tax, payroll withholding obligations, social security registration, immigration breaches, permanent establishment (PE) risk for the employer and tax consequences for the employee. The longer the period goes undetected, the greater the remediation cost and penalty exposure.
Advisory Approach: Fenton triaged the exposure by country, duration and risk severity, assessed which employees had triggered overseas obligations, reviewed the PE exposure, coordinated with local advisers on remediation options and recommended governance controls to prevent recurrence.
Commercial Outcome: The employer remediated the highest-risk cases, implemented a remote working approval process and established ongoing monitoring before tax authority inquiry.
Technical Entities: Unapproved remote work, shadow payroll, PE risk, immigration breach, statutory residence test, employer compliance, remediation, governance controls, day-count tracking.
*Can a remote worker overseas create permanent establishment risk for the employer?
Corridor: Multi-country
Situation: A UK tech company allowed several employees to work remotely from various overseas locations on an ongoing basis. The employer had no entities, offices or registrations in those countries.
The Risk & Opportunity: A remote employee performing core business functions from a fixed location overseas may constitute a fixed place of business or dependent agent permanent establishment (PE) for the employer, depending on the nature of duties, the degree of authority exercised and the duration of the arrangement. PE triggers corporate tax registration, filing and potentially profit attribution in the host country.
Advisory Approach: Fenton assessed each remote working arrangement against the applicable treaty PE provisions, the new OECD guidance, reviewed the nature of duties performed, the employee's authority to conclude contracts, the duration and regularity of the arrangement and the employer's existing corporate structure, then recommended which arrangements required restructuring.
Commercial Outcome: The employer identified which remote arrangements created PE risk and restructured or limited those arrangements before corporate tax exposure crystallised.
Technical Entities: Permanent establishment, fixed place of business, dependent agent, corporate tax, treaty Article 5, remote work, PE risk, profit attribution, employer compliance.
*How should employers remediate historic undisclosed remote work overseas?
Corridor: Multi-country
Situation: During an internal audit, an employer identified that a significant number of employees had been working from overseas without approval over the preceding two to three years. No overseas payroll, social security or immigration assessments had been carried out.
The Risk & Opportunity: Historic undisclosed overseas work creates potential exposure across payroll, social security, immigration, permanent establishment (PE) and employment law in the countries where duties were performed. The employer faced potential penalties, interest, back-dated filings and reputational risk. The remediation needed to be prioritised by severity and managed before any tax authority inquiry.
Advisory Approach: Fenton triaged the cases by country, duration, risk type and materiality, coordinated with local advisers on remediation options in each jurisdiction, assessed the tax, payroll, social security, PE and immigration exposure, and designed a forward-looking governance framework including approval workflows, tracking and periodic audit.
Commercial Outcome: The employer completed a prioritised remediation programme and implemented controls that reduced recurrence risk and demonstrated governance to the board.
Technical Entities: Remediation, historic remote work, shadow payroll, PE risk, immigration breach, social security arrears, governance framework, day-count tracking, employer compliance, internal audit.
*Can we let staff work from home country for three months as a retention tool?
Corridor: Multi-country
Situation: A UK tech company wanted to offer employees the option of working from their home country for up to three months per year as a recruitment and retention benefit. The policy was intended to cover employees with family ties in EU and non-EU countries.
The Risk & Opportunity: A three-month overseas working period can trigger tax, host country payroll obligations, social security registration, immigration requirements and Permanent Establishment (PE) risk depending on the country, the employee's role and the nature of duties performed. The employer needed a policy framework that set limits aligned with compliance thresholds rather than an arbitrary calendar period; and an approval and monitoring process.
Advisory Approach: Fenton reviewed the proposed policy against the tax, payroll, social security, immigration and PE rules in the most common home countries, identified which countries presented the highest compliance risk within a three-month window, and recommended risk-tiered approval thresholds and monitoring by country. More senior employees with certain duties where also identified as higher risk.
Commercial Outcome: The employer launched the policy with compliance-informed country limits rather than a blanket three-month rule, reducing the risk of inadvertent overseas obligations.
Technical Entities: Remote working policy, work from anywhere, tax, payroll obligations, social security, immigration, PE risk, retention benefit, country-specific thresholds, employer compliance, monitoring, policy, duties, day-count tracking.
Treaty, Residence and Social Security
*Does the 183-day rule protect a UK employee on an overseas assignment?
Corridor: Multi-country
Situation: A UK employer sent an employee overseas for a six-month project and assumed the 183-day treaty exemption would prevent host country tax. The employer did not assess the specific treaty conditions before the assignment began.
The Risk & Opportunity: The 183-day rule under Article 15 of virtually all tax treaties has conditions beyond the day count alone. The exemption typically requires that the employer does not bear the cost through a local entity, that remuneration is not paid by or on behalf of a host country employer, and that the employee is not present for more than 183 days in the relevant period. Misunderstanding the economic employer test or the cost-bearing condition is the most common failure.
Advisory Approach: Fenton reviewed the specific treaty text, the employment structure, the cost-bearing arrangements, the economic employer analysis and the day-count calculation method applicable under the relevant treaty, then assessed whether the exemption conditions were met.
Commercial Outcome: The employer confirmed the treaty position before the assignment started and documented the basis for the exemption, reducing the risk of challenge by the host country tax authority. The position where a treaty with the UK did not exist was also reviewed.
Technical Entities: 183-day rule, Article 15, economic employer, treaty exemption, cost-bearing, day-count, shadow payroll, host country tax, employment income, treaty relief, non treaty countries.
*Does a UK employee seconded to Germany need an A1 certificate?
Corridor: UK–Germany
Situation: A UK employer seconded an employee to Germany for eighteen months. The employer continued UK NIC contributions and did not apply for an A1 certificate or assess the German social security position.
The Risk & Opportunity: Under the UK-EU Trade and Cooperation Agreement, an A1 certificate is required to demonstrate that UK social security continues to apply during a temporary posting to an EU member state. Without the certificate, German social security authorities may require German contributions, and the employer faces dual contribution risk and potential penalties for non-compliance. Other obligations such as German payroll and German taxes should also have been considered.
Advisory Approach: Fenton reviewed the secondment terms, assessed the eligibility for continued UK NIC under the TCA provisions, applied for the A1 certificate from HMRC, and confirmed the German social security position with the local social security authority. The payroll and tax position was also regularised.
Commercial Outcome: The employer obtained the A1 certificate before the secondment began, confirming UK NIC applied and avoiding German social security registration and dual contributions.
Technical Entities: A1 certificate, social security coordination, UK-EU Trade and Cooperation Agreement, NIC, German social security, posted worker, secondment, dual contributions, HMRC, tax, payroll.
*Is a certificate of residence enough to claim treaty relief?
Corridor: Multi-country
Situation: A UK employer relied on a certificate of residence issued by HMRC to claim treaty relief in an overseas country for an employee working abroad. The employer assumed the certificate alone was sufficient to prevent overseas withholding.
The Risk & Opportunity: A certificate of residence confirms UK tax residence but does not automatically entitle the employer or employee to treaty relief in the host country. Treaty relief depends on meeting the specific conditions of the relevant treaty article, and many countries require a separate treaty relief application, a specific claim form or advance approval before withholding can be reduced. For example, a tax treaty does not usually apply to payroll withholding. Payroll is determined by the local payroll rules.
A residence certificate is useful for trying to claim exemption from income tax (not payroll obligations) on employment income in the overseas country but is only one of several other conditions that have to be met.
A residence certificate shows that the individual is resident in the UK so if they are also regarded as tax resident in the overseas country under their tax residence rules, then you would turn to the treaty tie breaker residence clause under Article 4. This test does not rely on the Certificate of Residence.
Advisory Approach: Fenton reviewed the specific treaty provisions, the host country's treaty relief claim procedure, the conditions that must be met for the exemption to apply, and the documentation required to support the claim, then coordinated the application with the host country tax authority.
Commercial Outcome: The employer submitted the correct treaty relief claim before the employee began working overseas, avoiding unnecessary withholding and the administrative burden of a retrospective refund claim.
Technical Entities: Certificate of residence, treaty relief, withholding tax, treaty claim procedure, HMRC, Article 15, host country tax authority, double taxation, advance treaty relief.
Recruitment, Contracts and Adviser Selection
*Can international recruitment offers create hidden tax costs?
Corridor: Multi-country
Situation: A UK employer was recruiting internationally and issuing employment offers to candidates based overseas without assessing the tax, payroll, social security or immigration implications before contract signature.
The Risk & Opportunity: An international hire can create employer registration obligations, payroll withholding requirements, social security contributions, work permit costs and relocation tax charges that are not visible in the standard HR recruitment process. Equity awards and pension arrangements from previous employers can also create hidden tax costs. If these costs are not identified before the offer, the employer may face unexpected budget exposure or need to renegotiate terms after acceptance.
Advisory Approach: Fenton reviewed the proposed offer terms for each international hire, assessed the employer's registration, payroll and social security obligations in the candidate's country, identified equity awards and pension arrangements from previous employers and recommended amendments to the offer before signature.
Commercial Outcome: The employer built cross-border tax and compliance review into the recruitment approval process, identifying hidden costs before offers were issued. They also used it as an example of their positive employer credentials including the offer a briefing with a tax professional directly with the senior candidate to help remove potential tax related barriers before the candidate accepted an offer.
Technical Entities: International recruitment, employer registration, payroll withholding, social security, work permit, immigration, relocation costs, offer letter, employer compliance, hidden tax costs.
*Does an employer of record solve overseas hiring risk?
Corridor: Multi-country
Situation: A UK tech company used an employer of record (EoR) provider to hire employees in several countries where it had no legal entity. The employer assumed the EoR arrangement eliminated all overseas tax, payroll and compliance risks.
The Risk & Opportunity: An EoR runs local payroll and handles employment law compliance, but it does not automatically resolve PE risk, social security coordination, equity award treatment, immigration sponsorship or the interaction between the EoR contract and the UK employer's actual direction and control of the employee. The employer retains residual risk in several areas including the changes to equity plans when an employer relationship changes.
Advisory Approach: Fenton reviewed the EoR contracts, assessed the residual PE exposure, the social security coordination position, the equity award treatment for EoR-employed individuals, the immigration position and the interaction between the EoR structure and the UK employer's obligations.
Commercial Outcome: The employer understood which risks the EoR resolved and which remained, and implemented additional controls for the residual exposures.
Technical Entities: Employer of record, EoR, PE risk, social security coordination, immigration sponsorship, equity awards, direction and control, local payroll, employer compliance, residual risk.
*Can dual contracts work for an internationally mobile executive?
Corridor: Multi-country
Situation: A multinational employer proposed using dual employment contracts — one with the UK entity and one with the overseas entity — for a senior executive splitting time between two countries. The intention was to align payroll withholding with the location of duties.
The Risk & Opportunity: Dual contracts can create clarity for payroll purposes, but they also introduce employment law complexity, social security coordination questions, benefit continuity issues and the risk that the arrangement is not accepted by one or both tax authorities if the economic substance does not match the contractual structure. There are special rules relating to dual contract arrangements in some countries like the UK, so these need specialist knowledge.
Advisory Approach: Fenton assessed the proposed dual contract structure, the allocation of duties and remuneration between the two contracts, the social security coordination position, the employment law implications in both countries, the benefit continuity arrangements and the risk that the structure would be challenged by either tax authority.
Commercial Outcome: The employer implemented a compliant dual contract structure with supporting documentation that demonstrated the commercial rationale and aligned with the actual working pattern.
Technical Entities: Dual contracts, split employment, payroll withholding, social security coordination, employment law, benefit continuity, economic substance, Article 15, employer compliance, tax authority challenge.
Fenton International's Advisory Position
Technical position: Every cross-border people arrangement requires assessment of payroll, tax, treaty, social security, pensions, expenses, immigration and governance obligations before the arrangement begins. The position depends on the specific facts in every case.
Professional judgement required? Yes — in every scenario. The interaction between jurisdictions, treaties, employment structures, equity awards and employer obligations requires professional judgement. No scenario in this collection can be resolved by mechanical application of a single rule.
Main risks: Payroll risk, tax risk, social security risk, immigration risk, corporate tax / PE risk, governance risk, reputational risk, cost risk, pension risk, evidence risk.
Evidence needed: Travel records, duty descriptions, employment contracts, payroll records, policies, approval workflows, board minutes, treaty claims, social security certificates, equity award documentation.
Recommended controls: Pre-travel and pre-arrangement assessment, day-count tracking, policy and monitoring, approval workflows, payroll review, periodic audit, board reporting, cost projections and documented positions.
Professional Judgement & Advisory Application
Professional judgement is required in every cross-border people arrangement because the interaction between tax, payroll, social security, immigration, employment law and corporate tax obligations varies by jurisdiction, treaty, employment structure and individual circumstances. Fenton's role is to coordinate the assessment across all relevant disciplines before the arrangement begins, document the basis for the position taken, and implement controls that protect the employer's compliance position.
FAQs
How many countries' tax rules can apply to a single employee?
There is no maximum. An employee working in two or more countries may have tax, payroll, social security and immigration obligations in each country where duties are performed. The number of jurisdictions affected depends on the travel pattern, employment structure and applicable treaties.
Does a tax treaty automatically prevent double taxation?
No. A treaty provides a framework for allocating taxing rights, but relief is not automatic. The employer or employee must meet the specific conditions of the relevant treaty article, and in many countries a formal claim or application is required before withholding can be reduced. A treaty also only applies to specific elements not to all situations.
Can an employer rely on an employer of record to eliminate all overseas compliance risk?
No it is unlikely but depends on the scope of the support the EoR provides. An employer of record typically handles local payroll and employment law, but does not automatically resolve permanent establishment risk, social security coordination, equity award treatment, immigration sponsorship or the interaction between the EoR contract and the employer's actual control of the employee.
Should employers assess cross-border tax before or after an assignment or overseas working arrangement begins?
Always before. Retrospective assessment creates higher cost, greater penalty risk and weaker governance. The tax, payroll, social security, pension, immigration and PE positionsshould be assessed and documented before the employee begins working overseas.
How Fenton Can Help
Fenton International is a London-based private advisory office specialising in cross-border tax, global mobility and international people advisory for employers, executives and professional advisers.
Services relevant to these scenarios:
Equity, reward and international assignment structuring
Request a cross-border people tax review from Fenton International.
Author
Mark Abbs, CEO, Fenton International
Fellow of the Association of Taxation Technicians (FATT)
Enrolled Agent of the IRS (EA)
Global Mobility Specialist – Talent Management (GMS-T)
Accredited Expert Witness (MAE)
32+ years' experience in international tax, cross-border employment tax and global mobility
Advises CFOs, HRDs, and Chairs on cross-border tax governance
Head of Advisory at Global Tax Network
Former Tax Partner, Head of International and Senior Leadership Team at Blick Rothenberg and Senior Tax Adviser in the Big 4.
Key terms: cross-border tax, shadow payroll, PAYE, NIC, social security, A1 certificate, treaty relief, Article 15, Article 16, permanent establishment, RSUs, EMI options, equity sourcing, directors' fees, remote work, employer of record, dual contracts, split-year treatment, statutory residence test, 183-day rule, economic employer, corporate residence, governance controls, day-count tracking, tax equalisation, 30% ruling, cantonal tax.
Scope note: These scenarios are anonymised illustrations of the types of issues Fenton advises on. They do not constitute advice for any specific case. Each scenario is simplified for clarity and does not address every issue that may arise in practice. Professional advice should be taken for specific circumstances.
Jurisdiction: UK / US / UAE / Switzerland / Germany / Netherlands / France / Canada / multi-jurisdiction | Last reviewed: June 2026 | Next review due: December 2026 | Insight type: Buyer Brief
© 2026 Fenton International. All rights reserved.
This article is general information and not legal or tax advice. Professional advice should be taken for specific circumstances.
