International tax support that
brings clarity across borders

Summer Tax Illustration

Navigate with clarity
& confidence

Expanding internationally brings big opportunities and complex challenges.

Our International Services team helps you navigate these with clarity and confidence. From setting up overseas operations to managing cross-border tax, we support SME businesses with global ambitions.

International Services

Our international specialists combine technical know-how with on-the-ground experience to help you succeed in global markets. We work closely with our worldwide network to deliver a seamless service, wherever you’re growing your business.

Summer International Services
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How we champion your business

Sumer Idea
Minimise tax leakage:

Cross-border structuring that protects your international tax position.

Sumer Shield
Stay compliant worldwide:

Transfer pricing and reporting support that meets global regulatory standards.

Sumer Detail
Trade with confidence:

Practical VAT and customs advice for smoother international operations.

Sumer Trophy
Grow with the right structure:

Expansion strategies aligned to your commercial and operational goals.

Powered by Global Connections

As proud members of the GGI Global Alliance, we give you direct access to one of the world’s largest networks of independent professional firms. Wherever you’re looking to grow, we can connect you to trusted local experts and ensure your international plans stay compliant, efficient and on track for success.

Grow your business globally

Meet the team

There are plenty of ways Sumer can make a difference to your business.

But if we had to pick one, it’s our people. With partner-led services from local experts in every region, we offer national scale and personal support from people who understand your sector and your community. From succession planning and exits to international growth, our specialists are here to help you make the big decisions with confidence.

Sumer - Team Image - HW Fisher - Adam Bonell

Adam Bonell

South East
Sumer - Team Image - HW Fisher - Adam Bonell

Adam Bonell

I head up our International Private client department looking after our clients who have cross border aspects to their affairs. The scope of the work is wide and includes UK residents with foreign assets as well as non-UK residents with UK assets.

With over 25 years of experience, I advise on all aspects of UK tax residency and dual residency including the nuances of UK law and the application of double tax treaties.

I have extensive experience advising non domiciled individuals on the remittance basis of taxation as well as helping clients navigate the new rules which come into effect in April 2025.

As well as looking after individuals and families, I work with businesses relocating employees or setting up businesses, whether in the UK or overseas.

Whether you need advice on completing your tax return, buying an overseas property or if you are thinking about leaving the UK I can provide practical guidance to help you navigate the often complex rules.

Although the main focus of my work covers ‘international’ matters, I have a large portfolio of clients advising on all aspects of UK taxation including income tax, capital gains tax and inheritance tax planning. Some notable areas of my practice are:

  • Domicile, remittance basis and Foreign Income and Gains regime
  • US Citizens in the UK
  • Pre and Post UK arrival planning
  • Leaving the UK and ceasing tax residency
  • Operation of UK double tax treaties including impact of dual tax residence
  • International employments
  • Overseas Workday Relief
  • Secondments and tax efficient global mobile employee program
  • Taxation of employee share awards and Long-Term Incentives
  • Tax compliance including coordination of overseas filing obligations
  • HMRC enquiry and correcting historic omissions
  • Cross-border estate planning
  • Capital gains planning and rebasing of foreign assets

Expertise

  • Income Tax
  • Capital Gains Tax
  • Inheritance Tax
  • Social Security
  • Domicile and Remittance basis
  • Statutory Residence
  • Repatriation advice
  • Double tax treaties
  • Tax equalisation
  • Personal Tax
  • Assisting taxpayers with HMRC Investigations
Sumer - Team Image - Monahans - Simon Tombs

Simon Tombs

South West
Sumer - Team Image - Monahans - Simon Tombs

Simon Tombs

As Managing Partner I head up the Monahans business.

I head our Professional Practices team and advise Solicitors and a range of owner-managed companies on all aspects of their businesses and practices.

I love to enable my clients to reduce costs, minimise the administration they undertake and allow them to have up to date information on their businesses, by providing our Monahans cloud accounting service. Depending on their needs, we will use the most appropriate packages, including FreeAgent and Xero as a part of our Business Bureau offering.

 

My background

I have worked for a number of professional firms ranging from large internationals to small local organisations and I also had a spell away from the accountancy profession in industry, which puts me in a great position to understand what our clients are looking for from their accountant.

Outside of work, my two teenage daughters keep me very busy. I also have a keen interest in property renovation and DIY in addition to car restoration. I like to get my hands dirty and do something slightly different than my day job.

 

  • Professional practices and small business
  • Advising solicitors and their practices
  • Owner managed businesses of all sizes
  • Cloud accounting
  • Payroll services
  • General accountancy services

Let’s get your business growing