About Fenton
International.
Fenton International operates through distinct divisions:
→ Fenton Advisory provides senior-led cross-border tax, global mobility and international people advisory through the Fenton Private Office model.
→ Fenton Investments and Fenton Real Estate reflect the firm's principal investment and long-term asset ownership activities.
Who we serve
Fenton Advisory advises individuals, employers, boards and professional advisers on internationally connected tax, payroll, social security, reward and governance matters.
Private clients, directors, founders and executives working anywhere, C-Suite and senior leaders, partners, non-executive directors.
Global mobility, reward, benefits, HR, and recruitment teams responsible for remote workers, international assignments and transfers.
In-house reporting and compliance teams managing cross-border payroll, withholding, and tax obligations arising from employees and directors.
C-Suite, Chairs, CoSecs, RemCo, NEDs, statutory directors with international reporting, reward and governance relating to their roles.
Teams appointing, benchmarking, or managing external tax, global mobility and reward advisory providers.
UK and overseas tax advisers, lawyers, immigration specialists, relocation, recruitment firms seeking cross-border technical support or partnerships.
Who leads Fenton International
Mark Abbs is CEO and Founder of Fenton International. He has more than 32 years of experience in international tax and global mobility, including 14 years as a Tax Partner and Head of International at Blick Rothenberg (part of Azets), where he also built and led the firm's global mobility tax practice and was a member of the Senior Leadership Team. He was a senior advisor in Big 4 firms for over 16 years (PwC, EY and Arthur Andersen). He is a Fellow of the Association of Taxation Technicians, an IRS Enrolled Agent, an accredited expert witness (MAE). He is a Global Mobility Specialist -Talent Management (GMS-T) and has a Diploma in Technology and Taxation (DITT) with the Chartered Institute of Taxation. He is also Head of Advisory at GTN UK, Strategic Adviser at the start-up AI firm Echeva. Mark is a member of Mensa, and an Ambassador for the Global Wellness Institute.
What Fenton Advisory does
Fenton Advisory advises on cross-border tax, residence, treaty interpretation, PAYE, National Insurance contributions, social security coordination, remote and hybrid working, international assignments, tax equalisation, equity and share schemes, pensions, board and NED fees, remuneration & expenses, employer compliance, payroll advisory, multi-adviser coordination, and the review and challenge of AI-generated or adviser-prepared analysis.
Core advisory areas include:
→ Cross-border personal tax and residence
→ Treaty relief and dual residence disputes
→ International payroll, withholding and reporting
→ Social security taxes and coordination
→ Remote and hybrid worker compliance (work from anywhere)
→ International assignment structuring, tax equalisation and policies
→ Equity award and share scheme taxation across jurisdictions
→ Board remuneration, NED fees and governance
→ Employer compliance and risk assessment
→ Multi-adviser coordination and quality oversight
→ Review and challenge of AI-assisted advisory work
When to choose Fenton Advisory
You may need Fenton Advisory if:
→ the issue involves the UK, US or more than one country
→the person is senior, mobile, remote-working, a director, NED, founder or executive, leadership, HR, on or going on an assignment, or an expatriate
→tax, payroll, social security, immigration, employment law or equity issues overlap
→different advisers are giving partial or inconsistent answers
→the business needs a defensible strategic position before making a decision
→the matter has board, governance, HMRC, reputational or employee-relations sensitivity
→you need an experienced adviser to review, challenge or coordinate advice
Fenton Advisory may not be the right fit if:
you are looking for a cheap tax return preparer
you need high-volume expatriate tax return processing
you want informal advice without an engagement
the matter is purely immigration, purely employment law, or purely payroll processing with no cross-border tax or social security issue
How Fenton Advisory fits within the advisory market:
The cross-border tax and global mobility advisory market is served by several types of provider. Each has strengths. The right choice depends on the complexity of the matter, the seniority of the individuals involved, the number of jurisdictions, and whether the issue requires process delivery, technical advice, or senior judgement across multiple workstreams.
Mid-tier accounting and tax firms
Mid-tier firms can offer strong client relationships, local tax capability and access to specialist teams. They may be well suited to recurring tax compliance, owner-managed businesses and broader accounting support.
Fenton Advisory is designed for matters that might additionally include cross-border tax, payroll, social security taxes & pensions, employment-related reward & HR, board governance and adviser coordination needs. It provides senior oversight across workstreams where the issue does not sit neatly within one compliance process.
Large professional service firms
Large professional services firms are often well suited to multinational groups, listed companies, large assignee populations and matters requiring global scale. They can provide specialist teams across multiple disciplines and jurisdictions.
Fenton Advisory is different. It is designed for complex, senior or non-standard matters where the client needs experienced judgement, direct senior involvement and a clear single point of advisory coordination, rather than a volume-led delivery model.
Specialist advisory firms and independent practitioners
Specialist firms and independent practitioners can be technically strong in defined areas of cross-border tax, global mobility, payroll, social security, reward or employment-related advisory work.
Fenton Advisory was built around a Private Office model. It is intended for situations where the client needs integrated advice across multiple disciplines, with one senior adviser coordinating the judgement, workstreams and external specialist input where required.
Technology-led mobility providers
Technology-led mobility providers can be effective where the main need is workflow, tracking, document management, reporting and process standardisation. These platforms can work well for straightforward assignment populations and repeatable mobility processes.
Fenton Advisory uses technology to support experienced professional judgement. Technology helps identify cross-disciplinary interactions, but the final assessment remains senior-led, personal and advisory-led.
Tax return and payroll advisers
Tax return and payroll bureaus each play an important role processing tax returns, payroll and reporting obligations. They are often efficient for recurring, repetitive or standardised matters. They are not usually designed to lead strategic advisory work, challenge existing positions, coordinate multiple advisers or advise on matters requiring senior professional judgement.
Fenton Advisory does not compete with them. It works alongside them where a matter requires advisory review, technical challenge, risk assessment or coordination that a compliance or payroll process alone cannot provide.
How Fenton Advisory works:
Fenton Advisory delivers through three service levels, matched to the depth of support the matter requires.
Case Review
Senior judgement on analysis, research or AI-generated work already prepared by the client or another adviser. The client has done the initial work. Fenton applies expert challenge, identifies gaps, tests assumptions and provides a confirmed position the client can act on with confidence.
Lead Counsel
Full-service advice where Fenton leads the analysis, coordinates specialist input and provides a clear recommended position. From initial question through to final resolution. The client receives one coherent view across all relevant disciplines.
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Discovery
Structured review of documents, payroll records, travel data, employment arrangements, equity records or adviser correspondence to identify cross-border tax, payroll, social security, immigration, reward or governance risks and opportunities. Designed to sit alongside existing compliance relationships.