About
We are a UK based tax firm providing UK and US personal tax advisory and compliance services.
We provide bespoke, clear and practical solutions to our clients as they navigate the ever-growing complex UK and US personal tax environment.
We do this by providing a high level of client service, working alongside our clients to add clarity to their UK/US tax position, building a long standing trusted relationship.
We offer a fixed fee service to our clients for both advisory and compliance matters, based on the complexity of the work required. We will quote for work upfront for full transparency, avoiding any unexpected bills.
WHY CHOOSE STERLING TAX?
We are UK and US qualified tax experts with over 30 years of combined tax experience. Having worked within the Big 4 and market leaders throughout our respective careers we understand the importance of client relationships, and how these are unique to each and every client and not off the shelf.
We're commited to a personalised, proactive service to our clients, understanding their specific circumstances and goals and a providing bespoke client relationship.
Long standing client relationships are the cornerstone of our business.
As founders, we have both worked together during our careers and have continually noted during that time how important the client is and how it should forever be at the forefront of any consideration. We apply our respective skill set to each client, ensuring that every client is aligned to the most appropriate advisor, although our skill sets are different and complement each other, where we overlap is providing a sterling tax service to our clients.
Meet the Team
Mark Allsopp
Director
Mark.Allsopp@sterling-tax.co.uk
020 4591 3293
I am the co-founder of Sterling Tax, having started in tax in 2007 at Frank Hirth PLC working at various firms (including the Big Four) providing tax advice and compliance to high net worth individuals.
Throughout my career I have supported many clients with all manner of UK/US tax considerations. I specialise in dual residents, expats, US expatriation, inbound individuals into the UK or the US, sale of property, and review of investment structures for optimisation of tax efficiencies.
I hold relevant qualifications in both the UK and US (ATT and EA, respectively). My personal goal is be a fully trusted tax advisor to my clients offering the highest level of tax guidance and support, working with my clients on an ongoing basis managing their tax position.
Outside of work, I enjoy being a “nerd”, gaming (both retro and current) as well as spending quality time with my wife, two young children and two overly excitable dogs. I have been told I enjoy a pint, occasionally.
Rikveer Mangat
Director
Rikveer.Mangat@sterling-tax.co.uk
020 4591 3287
I am the co-founder of Sterling Tax, with over a decade of experience in international tax advice.
Prior to establishing the firm, I have spent the majority of my career at Big Four accounting firms, where I developed deep expertise in cross-border taxation, compliance, and strategic planning for high-net-worth individuals and their families.
I specialise in the unique tax challenges faced by clients with UK-US ties, including expatriates, dual residents, and individuals with complex international holdings, such as carried interest and co-investment.
I am known for skills in managing intricate financial situations, often involving multi-jurisdictional compliance, tax-efficient structuring, and wealth preservation.
I hold relevant qualifications in both the UK and the US (ATT and EA, respectively). My personal goal is to provide the highest level of personalised service, helping clients successfully navigate the complexities of US-UK taxation and secure their financial future.
Outside of work I enjoy unwinding by catching a football match, exploring the local vibrant restaurant scene, and spending quality time with family and friends.
Chris Gilmartin
Director
chris.gilmartin@sterling-tax.co.uk
020 4591 3287
I joined Sterling Tax as Director in February 2026, having previously worked with Mark and Rik at both Frank Hirth and EY for many years. I began my career as a graduate in the US–UK private client team at Frank Hirth in 2012.
Over the years, I have advised a wide range of globally mobile clients, including Ultra High Net Worth Individuals, cross‑border families, and senior professionals in the technology and banking sectors. My specialist areas include deferred compensation, pension planning, and reviewing investments for tax efficiency—particularly in relation to Passive Foreign Investment Companies (PFICs).
My core objective is always to minimise a client’s overall US and UK tax exposure, eliminate double taxation, and ensure their affairs are structured as efficiently as possible—all while providing exceptional and timely client service.
I hold professional qualifications in both the UK and the US (ATT and EA, respectively).
Outside of work, I enjoy travelling, keeping up with politics and current affairs, and reading fiction. I’m also a keen foodie and love exploring new restaurants, as well as getting out for long walks whenever I can.
Nicola Allsopp
Office Manager
nicola.allsopp@sterling-tax.co.uk
020 4591 3287
I’m the Office Manager at Sterling Tax. Most of my career has been in the tax world within the Big Four, where I specialised in administration and finance.
At Sterling, I look after the day‑to‑day running of the office and manage client onboarding, making sure every new client gets a smooth, professional, and welcoming introduction to the firm.
Outside of work I have a busy life looking after two young children and if I get the chance I enjoy the theatre and catching up with friends!
SCHEDULE A CONSULTATION
At Sterling Tax, we believe every client deserves a bespoke approach. Contact us today to schedule a free consultation and discover how our team can help you confidently navigate the complexities of UK and US tax.