£20.5m Tax Bill: What the Addison Lee Founder’s Case Really Tells Us About Living Between Two Countries

£20.5 million.

That is the figure currently attached to a tax tribunal case involving Sir John Griffin, the founder of Addison Lee, after the First-tier Tribunal found that he was domiciled in England rather than Ireland for the tax years in question.

At first glance, it might seem like another story about a wealthy businessman and the much-discussed world of non-doms. But there is a much more interesting question hiding behind the headline. If the UK's non-dom rules have now been abolished, why should anyone still care about this case?

The answer is that the case highlights something that has always made international tax matters complicated: where you live, where you come from, where your family is, where you have assets and where you intend to make your permanent home can all matter — and they are not necessarily the same thing.

Sir John Griffin was born in England to Irish parents and retained a very strong connection with Ireland throughout his life. He had Irish property, an Irish bank account, Irish investments and significant personal and emotional ties to the country. He also held both Irish and British passports. So, from a personal perspective, his connection with Ireland was clearly substantial.

The tax dispute, however, was not simply about where he felt Irish or where he had family connections. It was about domicile. And that is where the case becomes particularly interesting. Griffin had filed his tax returns for the relevant years on the basis that he was domiciled in Ireland. HMRC disagreed and opened an enquiry in January 2016. The dispute ultimately concerned the years from 2013/14 through to 2019/20, and HMRC's closure notices increased his tax liability by £20,537,671.97.

The tribunal had to look at the evidence surrounding Griffin's life and determine where his legal domicile lay. And this wasn't a quick exercise. The tribunal considered evidence going back decades, including the circumstances of Griffin's father, his family life, property, business interests, social connections and his own intentions about where he planned to live. In fact, the case reached even further back than Griffin himself.

HMRC argued that Griffin had acquired an English domicile of dependence through his father, who had moved from Ireland to England in the 1930s. Although Griffin's father retained a strong affection for Ireland and continued to have connections there, his life became firmly established in England. He worked there, built a business, married, raised his family and acquired property. The tribunal concluded that his father had acquired an English domicile of choice before Griffin reached adulthood. That meant Griffin acquired an English domicile of dependence during his childhood.

But the tribunal didn't stop there. It also considered what Griffin's own position would have been if that first argument had not succeeded. And this is perhaps the most relatable part of the case. Griffin had spent the overwhelming majority of his life in England. His education, career, family life, business activities and wealth creation were centred there. He had founded and developed Addison Lee and continued to have significant connections with England.

He also retained his connection with Ireland and had expressed an intention to return there at some point. The tribunal accepted that his attachment to Ireland was genuine. But it drew an important distinction between wanting to return somewhere one day and having a settled intention to make that country your permanent home. In the tribunal's view, Griffin's intention to return to Ireland remained too vague and imprecise during the relevant period. His actions and circumstances continued to point towards England being his permanent home.

The appeal was therefore dismissed and the HMRC closure notices stood. That produced the £20.5m increase in tax liability. It is a fascinating case because it demonstrates just how much evidence can potentially be involved when tax authorities and taxpayers disagree about a person's domicile.

But there's an important 2026-sized caveat. The non-dom rules being discussed in this case are not the rules that apply today.

From 6 April 2025, the UK's previous non-domicile regime ended. The concept of domicile as a relevant connecting factor for this part of the tax system was replaced with a system based primarily on tax residence. The remittance basis was also replaced by the new four-year Foreign Income and Gains (FIG) regime for qualifying new UK residents. So you can't simply read the Griffin judgment and assume that the same rules apply to somebody moving to or living in the UK today.

That is precisely why the case is worth paying attention to. The terminology may have changed. The legislation has changed. The tax rules have changed. But the underlying problem hasn't disappeared. There are still plenty of people whose lives don't fit neatly into one country.

Perhaps you were born in the UK but now live overseas. Perhaps you've moved abroad but still own property in Britain. Perhaps your business is in one country while your family lives in another. Perhaps you spend significant amounts of time in different countries. Perhaps you have inherited assets overseas. Or perhaps you have returned to the UK after many years abroad and assumed that your tax position would be relatively straightforward.

It may not be. And this is where celebrity and high-profile tax cases can actually be useful. The headline might be about a businessman with a £20.5m tax dispute, but the underlying question is one that many ordinary people can recognise:

“I have strong connections to two countries. So where does that leave me for tax?”

The answer isn't necessarily determined by your passport. It isn't necessarily determined by where you own a property. And it certainly shouldn't be assumed simply because you consider another country to be your home. Your individual circumstances matter.

At The Tax Faculty, this is exactly the sort of situation where we believe specialist advice can add value. We regularly help clients with UK and international tax issues, including people living overseas, individuals with UK property and clients whose personal, business or financial affairs span more than one country. The important thing isn't simply to look at one part of the picture — it's to understand the whole situation and then establish which rules apply.

The Griffin case may involve a figure of £20.5 million, but you don't need to have millions in the bank for international tax to become complicated.

📞 If you're unsure about your UK or international tax position, The Tax Faculty can help you understand where you stand and what you need to consider.

Please note, the tax treatment of individuals with international connections depends on their individual circumstances and the tax years concerned. The non-dom rules referred to in the Griffin case applied to the historical tax years considered by the tribunal and are not the current UK regime.

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The Non-Dom Rules Have Gone — So Why Is This £20.5m Tax Case Still Relevant?

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