Cross-border tax, payroll & compliance advisory for in-house finance, tax, & payroll teams.
Fenton International advises in-house finance, tax, payroll, and HR compliance teams on cross-border employer obligations — including tax, PAYE (UK employer withholding tax), shadow and modified payrolls, NICs and social security taxes, long term incentive compliance reporting (stock options, RSUs, ISOs, EMIs), international pensions and international payroll coordination. The firm helps compliance teams identify, document, and resolve employer obligations arising from employees and directors working across borders (remote working, business trips, commuting, short term projects and formal secondments).
How the Fenton Private Office supports you
The Fenton Private Office supports finance, tax and payroll teams through the Employer Advisory Office — bespoke support where cross-border compliance obligations require senior judgement and technical co-ordination.
Three levels of support are available.
→ Case Review: senior judgement on a specific compliance question or position already prepared by your team.
→ Lead Counsel: full-service advice where Fenton leads the technical analysis and provides a clear recommended position on cross-border payroll, withholding, or reporting obligations.
→ Discovery: structured review of historic payroll records, filings and withholding positions to identify unreported exposure, missed relief, or social security certificate gaps.
When this needs immediate attention
Employees or directors are already working across borders and the payroll position has not been reviewed
1
What may be at stake? PAYE under-withholding, NIC exposure, reporting failures, PE risks, penalties, and interest may be accruing.
Why early advice matters? The longer the position remains unreviewed, the greater the cumulative exposure and remediation cost.
A tax year-end or filing deadline is approaching
2
What may be at stake? Reporting of awards, vests and exerciser, benefit and expense reporting, year end payroll reports, pension reports usually have fixed deadlines with automatic penalties for late filing.
Why early advice matters? Missing a deadline converts a manageable compliance task into a penalty and disclosure issue.
HMRC or other tax authority has asked questions or opened a review of international payroll or business traveller arrangements
3
What may be at stake? The response must be technically accurate, internally consistent, and properly documented.
Why early advice matters? Early specialist involvement protects the position and reduces the risk of escalation. Have someone experienced at your side.
Business travellers, international commuters & remote workers are visiting the UK from the overseas companies, but no tracking or reporting system is in place
4
What may be at stake? PAYE, NIC and other reporting obligations may exist for every visitor depending on duration, duties, and employer arrangements.
Why early advice matters? Implementing controls now is significantly cheaper than retrospective remediation.
Shadow payroll should have been operated but was not
5
What may be at stake? The employer may owe PAYE and NICs on employment income that did not have withholding, plus interest and penalties.
Why early advice matters? A remediation review can quantify the exposure and determine the best path to regularise the position.
Payroll, HR, tax, and finance teams disagree on who owns the cross-border compliance position
6
What may be at stake? Obligations may fall between functions, with no single team holding a complete overview.
Why early advice matters? A specialist review can create a clear position paper that all internal functions can work from.
Finance, tax, and payroll teams usually need to act quickly where withholding, reporting, or registration obligations may already have arisen or where a deadline is approaching.
Your issue → Fenton support → typical output
Employees working in the UK and you are unsure whether UK PAYE is required
→ Relevant Fenton support: UK PAYE obligation review
→ What you receive: Written analysis of the correct position - whether PAYE withholding, registration, or reporting is needed, with action points.
Shadow payroll may be needed but has not been set up
→ Relevant Fenton support: Shadow payroll assessment
→ What you receive: Analysis of whether a shadow payroll is required, which income is in scope, and implementation steps.
Business travellers visiting the UK with no tracking or HMRC reporting in place
→ Relevant Fenton support: Short-term business visitor compliance review (international business trips, commuters, remote working, short projects)
→ What you receive: Assessment of PAYE and reporting obligations, concession (appendix 4) eligibility, and recommended tracking controls.
Social security or national insurance position is unclear for cross-border workers
→ Relevant Fenton support: Social security and A1/Certificate of Coverage review. Certificates provide evidence of which country's social security legislation applies to a worker operating across EU/EEA and social security treaty countries.
→ What you receive: Analysis of which country's social security applies, whether certificates are needed, and next steps.
Year-end compliance — Various filing and obligations for internationally mobile employees
→ Relevant Fenton support: International year-end compliance support
→ What you receive: Identification of reportable items, preparation support, and deadline management.
Historic payroll operated without reviewing the international position
→ Relevant Fenton support: Retrospective compliance review
→ What you receive: Quantification of exposure, remediation options, voluntary disclosure assessment, and action plan.
Statutory directors (both execs and NEDs) paid across borders with unclear withholding or reporting position
→ Relevant Fenton support: Director payroll and reporting review
→ What you receive: Analysis of director fee taxing rights, withholding obligations, treaty positions, and reporting requirements.
Multiple internal teams involved but no one owns the integrated compliance position
→ Relevant Fenton support: Cross-function compliance coordination
→ What you receive: Position paper covering all employer obligations, allocated by responsible function, with action plan.
Other issues we can support you with →
Work from anywhere, remote working, digital nomads - employer compliance reporting
Employees or directors working across borders creating payroll, withholding, or reporting obligations (including remote workers)
Uncertainty over whether UK PAYE, shadow payroll, or payroll registration is required
Social security and national insurance exposure from cross-border working arrangements
Short-term business visitor tracking and HMRC reporting, including concession arrangements
Year-end compliance, reporting, and benefit expense obligations
Historic exposure where payroll has been operated without reviewing the cross-border position
International pension contributions - which are tax advantaged, which employer contributions are taxable
Dual payroll obligations and applications to improve cash flow
The correct reporting of ‘trailing income’ (income that was earned and paid, vested, exercised in different countries)
The correct sourcing of income across payrolls - for tax and for social security
Global share income reporting
Modified PAYE (EP6), Modified NICs (EP7A and 7B)
EP Appendix 4, Appendix 5, Appendix 6, Appendix 8
Localisation and permanent transfers
What a proper answer needs to cover
A reliable answer to most cross-border employer compliance questions usually needs to address:
Whether payroll withholding is required and on which income
Whether a shadow payroll is needed alongside a home-country payroll
Social security and national insurance — which country's regime applies and whether an A1 certificate or Certificate of Coverage should been obtained
Short-term business visitor reporting
Executive director and NED (non-executive director) reporting and withholding obligations
Benefit and expenses - year-end requirements for mobile employees
Interaction between the employer's payroll position and the employee's personal tax return
Whether historic exposure exists and what remediation options are available
Which internal function — payroll, tax, HR, or finance — is responsible for each obligation
International pension contributions - how are they treated
Consider ways to improve the employees cash flow where withholding is required in more than one location
The correct reporting of ‘trailing income’ for payroll and social security. Income that was earned in one country but was paid, vested, exercised in another.
The correct sourcing of income across payrolls - for tax and for social security
FAQs
Does an overseas employer need to operate UK PAYE for employees working in the UK?
1
In many cases, yes. Where an employee performs duties in the UK, the employer may have an obligation to withhold UK income tax and national insurance contributions — even if the employer has no UK entity. The obligation depends on the nature of the duties, the duration, the employment structure, and whether any HMRC concession arrangement applies. Caution is needed to avoid HMRC imposing payroll obligations for your employees on a UK based client.
When is a shadow payroll required?
2
A shadow payroll is typically required where an employee remains on a home-country payroll but has a UK tax liability on employment income arising from UK duties. The shadow payroll calculates and reports the UK tax position without necessarily making a separate payment — it ensures the UK withholding and reporting obligations are met alongside the home-country payroll.
What are the UK reporting obligations for short-term business visitors?
3
Employers may need to report short-term business visitors to HMRC, depending on the duration and nature of the UK work, the employer's PAYE status, and whether an EP Appendix agreement is in place. An AP Appendix arrangement provides certain PAYE/NIC relaxations for qualifying mobile employee but generally require annual reporting of certain details. Without agreements standard PAYE rules may apply from day one.
What should payroll teams do if cross-border withholding may have been missed?
4
Take advice before making corrections. Where PAYE or NIC may have been under-withheld on cross-border employment income, the remediation approach — including whether to make a voluntary disclosure to HMRC — depends on the size of the exposure, the period involved, and whether the employee's personal tax return has already accounted for the income. A specialist review can quantify the exposure and recommend the most appropriate path.
Who is responsible for cross-border payroll compliance — payroll, HR, tax, or finance?
5
In practice, the obligation falls on the employer as a legal entity, but the operational responsibility is often split across payroll, HR, tax, and finance functions — sometimes with no single team holding the complete picture. Where employees or directors work across borders, a clear allocation of responsibilities and a documented compliance position reduces the risk of obligations falling between teams.
Credentials and related insights
Fenton International is led by Mark Abbs, a senior international tax adviser with more than 32 years’ experience, with 14 years as Tax Partner, Head of International and Senior Leadership Team member at a UK Top 8 firm. Over 16 years as a Senior Adviser in Big 4 firms (PwC, EY). He is a Fellow of the Association of Taxation Technicians, an IRS Enrolled Agent, and an accredited expert witness.
Our Advisory team has held multiple senior leadership and board-level positions in HR, reward, and governance, managing budgets, delivering and setting strategy, and boardroom scrutiny. We bring the practical judgement of people who have owned the problem — not only advised on it.