Cross-border tax and global mobility advice for senior executives, directors, and private clients.
Fenton Private Office
The Fenton Private Office at Fenton International advises senior executives, statutory directors, non-executive directors, private company owners and internationally mobile individuals on:
UK-US taxes, cross-border tax, tax residence, equity, long term incentives (including stock options, RSUs, restricted shares) and other types of reward, international pensions, international social security taxes planning and compliance, tax equalisation policies, employer disputes, carried interest across borders, international business trips and commuting, work from anywhere, remote working and multi-adviser coordination globally.
We provide independent, senior-led advice to individuals managing personal tax obligations, planning and strategy across borders.
How the Fenton Private Office supports you
The Fenton Private Office supports individuals through our Private Executive Office — bespoke international tax, residence, employment, equity, dispute and advisory support for senior individuals whose personal, professional and financial affairs cross jurisdictions.
Three levels of support are available:
→ Case Review: if you have done your own AI research or received initial advice and want senior judgement to confirm, challenge or build on that work.
→ Lead Counsel: if you want Fenton to lead the analysis from the outset and provide a clear recommended position.
→ Discovery: if you want a structured review of your existing tax filings, employment arrangements, equity records or adviser correspondence to identify risks and missed opportunities.
When this needs immediate attention
→ A move to or from the UK is approaching
Q: What may be at stake? Residence status, compliance, arrival/departure timing, and planning decisions may be fixed once the move occurs.
Q: Why early advice matters? Planning options narrow significantly after the event.
→ Equity or deferred compensation is vesting or you will exercise during or after an international move
Q: What may be at stake? Income may be taxable in more than one country with no credit or relief if not structured in advance. Tax advantaged schemes may not be effective overseas.
Q: Why early advice matters? Tax cost can increase materially if vesting, exercise or sale timing is not reviewed before the event.
→ A UK tax return filing deadline is approaching
Q: What may be at stake? Penalties and interest accrue automatically for late filing; voluntary disclosure is treated more favourably than discovery.
Q: Why early advice matters? The longer the delay, the higher the cost and the weaker the position. Alignment with filing obligations in other locations is critical to avoid unnecessary tax costs.
→ Employer-provided advice covers only employment income
Q: What may be at stake? Property, investments, pensions, family circumstances, and non-employment income may create separate obligations.
Q: Why early advice matters? Personal exposure can exist even when the employer's compliance position is correct. The employers position may actually increase your personal tax costs.
→ Advice has been received from separate advisers in different countries
Q: What may be at stake? Positions may conflict, overlap, or leave gaps that no single adviser has identified.
Q: Why early advice matters? An integrated review can surface problems before they become disputes and save unnecessary tax and duplicate adviser costs.
→ HMRC, IRS or other tax authority has opened an enquiry or issued a penalty notice
Q: What may be at stake? The response must be technically accurate, consistent with the filings, and properly documented.
Q: Why early advice matters? Early specialist involvement protects the position and reduces the risk of escalation. Get someone with experience on your side.
The earlier advice is taken, the more options are usually available. Once a move has happened, equity has vested, a tax year has closed, or HMRC has opened an enquiry, the issue often shifts from planning to remediation.
Other issues we specialise in:
→ Founders, C-Suite, board directors looking to do their UK role remotely from another country or countries: planning, structuring, costings with a holistic view of all jurisdictions involved. Employer communication strategies.
→ Moving to or from the UK, or deciding whether to relocate or commute to the UK
→ UK residence, the Foreign Income and Gains regime, and personal tax reporting obligations
→ Equity, share options, RSUs or deferred compensation vesting or being exercise across borders
→ UK/US (Federal, State and City) tax exposure for US citizens or green card holders in the UK, and UK residents working in the US
→ Director, NED, or board fees, travel and accommodation expenses in more than one jurisdiction
→ Employer-provided tax advice that may not cover the full personal position
→ Disputes with your employer, including tax equalisation, tax protection and tax gross-ups managed by other advisers
→ International social security taxes, NICs - issues, planning and compliance
→ Pensions you contributed to in different countries and retirement strategies. Where will you pensions be taxed and how? Any planning?
Your issue → Fenton support → typical output
Moving or committing to or from the UK
1
Relevant Fenton support: Residence and relocation tax review
What you receive: Written residence position, statutory residence test analysis, action points. Overview of all jurisdictions involved.
Working or earning in more than one country
2
Relevant Fenton support: Cross-border personal tax advisory
What you receive: Tax analysis covering all relevant jurisdictions, coordinated position.
US citizen or green card holder in the UK, or UK resident working in the US.
3
Relevant Fenton support: UK/US tax alignment and advice.
What you receive: Coordinated UK and US tax analysis, treaty positions, foreign tax credit review.
Equity vesting or exercise during international working (remote work, assignment, commuting)
4
Relevant Fenton support: Equity and reward tax review
What you receive: Jurisdictional taxing rights analysis, employer withholding review, planning options.
NED or director fees from more than one country
5
Relevant Fenton support: Residence and relocation tax review
What you receive: Written residence position, statutory residence test analysis, action points. Advice on all forms of director income including fees, travel and accommodation expenses, consulting income and stock options.
Leaving the UK with property, pensions, or investments
6
Relevant Fenton support: UK departure and ongoing obligations review
What you receive: Departure analysis, continuing UK obligations, capital gain tax (CGT) and income tax position.
Advice from multiple firms does not join up
7
Relevant Fenton support: Multi-adviser coordination. Overview of all jurisdictions involved.
What you receive: Integrated position paper identifying gaps, conflicts, and missing analysis.
HMRC, IRS, tax enquiry or penalty relating to international tax
8
Relevant Fenton support: Enquiry and dispute support
What you receive: Technical defence, correspondence management, expert witness where required.
What an answer needs to cover:
A reliable answer to most cross-border personal tax questions usually needs to address:
Tax residence in each relevant country
The Foreign Income and Gains (FIG) regime, a four-year residence-based regime for new UK arrivals, replacing the former domicile-based remittance basis from April 2025
Inheritance tax position, where domicile and deemed domicile status remain relevant during the transitional period
Employment income sourcing and split-year treatment, meaning dividing a tax year between resident and non-resident periods
Equity, share options, and deferred compensation across jurisdictions
Treaty relief and foreign tax credit positions
Social security and national insurance contributions
Property, pensions, and investment income
Employer payroll and reporting obligations
Timing of arrival, departure, or triggering event
Interaction between personal obligations and employer obligations
FAQs
Do I need UK tax advice before commuting or moving to or from the UK?
1
Yes. UK tax residence, the Foreign Income and Gains regime, which replaced the former domicile-based remittance basis from April 2025, social security tax, pensions, long term incentives and reporting obligations are significantly affected by decisions made before arrival or departure — including timing, asset planning, and employment structure. Advice obtained after the event is often more limited in what it can achieve.
Does my employer's tax adviser cover my personal position?
2
Not always. Employer-appointed advisers typically focus on the employer's compliance obligations — payroll, reporting, social security — rather than the individual's wider personal affairs. Property, investments, pensions, family circumstances, and non-employment income may not be covered.
The taxation of share options, restricted stock units (RSUs), and deferred compensation across borders depends on the type of award, the vesting period, the countries worked in during that period, and the applicable tax treaties. Each jurisdiction may have a taxing right. The analysis needs to consider both employer withholding obligations and personal return positions.
How is equity taxed when I work in more than one country?
3
4
Do US citizens in the UK need coordinated UK and US tax advice?
Yes. US citizens and green card holders are subject to US worldwide taxation regardless of where they live. UK and US advice must be aligned to avoid double taxation, identify treaty positions, claim foreign tax credits correctly, and manage US-specific reporting such as FBAR and FATCA. Local and States taxes need to be considered. Tax advantaged schemes, elections, stock valuations, timings may all be different in the two countries. ISAs and pensions whilst tax efficient in the UK, are treated differently in the US.
What should I do if I receive an HMRC, IRS or tax enquiry about an international tax matter?
5
Take professional advice before responding. Tax enquiries into international tax positions can involve residence, employment income, social security, capital gains, offshore income, and reporting failures. The response needs to be technically accurate, consistent with the filed return, and properly documented by someone with sufficient experience of these matters.
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.
