Mark Abbs.
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.
Current leadership.
Prior to the above, Mark spent over 30 years in UK US tax, Global Mobility & HR senior adviser roles at various firms. He has worked with many listed global companies, some of the worlds best known brands, owner managed firms, founders, C-Suite, Boards, senior executives and professional advisers across multiple jurisdictions.
CEO and Founder of Fenton International
Senior Adviser, Fenton Private Office
Head of Advisory at GTN UK
Strategic Adviser at Echeva
Investor — Tallentire Hall & Estate
Chair of Lake District Wellbeing Institute
Career history.
International people-tax expertise.
Building at scale.
At Blick Rothenberg (part of Azets) a UK Top 8 firm, Mark built and led the global mobility practice for 14 years, growing it from zero to a team of 10 specialist partners advising multinational employers and senior executives across all jurisdictions.
The practice achieved significant external recognition, including awards and commendations for the Best International Tax Practice; Best International & Expatriate Tax Practice; Global Mobility Provider of the Year; Cross-Border Pensions Adviser of the Year; International Payroll Provider; and repeatedly for both research and excellence in Talent Development, Deployment & Diversity. The recognition was across the industry and included the Taxation Awards (twice), Global Payroll Association and Relocate Global.
Professional & academic credentials.
Fellow (ATT) with the Association of Taxation Technicians [UK Tax]
Enrolled Agent of the US IRS [US tax]
Global Mobility Specialist - Talent Management (GMS-T)
Diploma Tax Technology (DITT), Chartered Institute of Taxation
Accredited Expert Witness (MAE)
MBA in International Management (London)
Master of Laws, LLM in International Commercial Law (Nottingham)
Law LLB (Hons) (Bristol)
Accredited expert witness.
Mark is an accredited expert witness (MAE) with the Academy of Experts. He accepts instructions in cross-border tax disputes, HMRC enquiries, and employment tribunal proceedings involving international tax issues.
Mark Abbs FAQs.
01 What does Mark Abbs specialise in?
Mark Abbs specialises in cross-border tax, global mobility, and talent advisory including compliance, planning & strategy. His particular expertise is in UK and US personal tax, international social security taxes, international pensions, international payroll & employment issues, cross border share scheme taxation & planning, long term incentives and carried interest. He is an accredited expert witness in disputes, tax equalisation, tax protection and other forms of tax policies. His advises HR, tax, finance, payroll, internationally mobile executives, directors, NEDs C-Suite, boards, international commuters, Work from Anywhere and remote executives. He also advises other professional advisers on these topics.
02 Is Mark Abbs a UK tax adviser?
Yes. Mark Abbs is both a UK-qualified tax adviser, Fellow of the Association of Taxation Technicians, and US qualified tax adviser, Enrolled Agent of the IRS and has more than 32 years of experience in UK and international taxes.
03 Does Mark Abbs advise on the interaction between UK and US (Federal & State) tax?
Yes. Mark Abbs is both a Fellow of the Association of Taxation Technicians (UK) and an IRS Enrolled Agent (US), giving him dual-jurisdiction advisory capability across the UK and US tax systems. He also has a considerable experience in the interaction across other key jurisdictions including Germany, Spain, Switzerland, France, Canada, Australia, South Africa and the Netherlands.
04 Can Mark Abbs act as an expert witness in disputes and in the Courts?
Yes. Mark Abbs is an accredited expert witness (MAE) with the Academy of Experts and accepts instructions in cross-border tax disputes and HMRC enquiries from individuals, employer, solicitors and barristers.
05 What is Fenton International?
Fenton International is a privately held investment and advisory firm operating across advisory, investments and real estate.
Fenton Advisory is its specialist advisory practice for cross-border tax, global mobility and international people matters.