Billionaires are leaving the UK. Why?
High-profile billionaires are relocating from the UK to Monaco, Greece and Switzerland. But how much tax revenue is Britain actually losing, and how much of the exodus is really driven by tax?
Billionaires are leaving the UK. But how much is the Treasury really losing?
🇬🇧 The headlines keep coming. → David Reuben, joint second on the Sunday Times Rich List with a family fortune of almost £28bn, has moved to Monaco. → Chris Rokos, founder of Rokos Capital Management, is moving his tax residence to Greece and opening an office in Athens. → Lakshmi Mittal became a Swiss tax resident late last year and is expected to spend much of his time in Dubai. Rokos is the headline number. According to the Sunday Times Tax List, he paid an estimated £330 million in UK tax in the last tax year. That is a significant sum, but it does not mean the UK automatically loses £330 million every year from now on. Income fluctuates, UK-source income can remain taxable, and the Statutory Residence Test can bring people back into the UK tax net with surprisingly few days in the country.
How many HNWIs and UHNWIs are actually leaving?
The honest answer: nobody knows precisely. → Henley & Partners forecast a net outflow of 16,500 millionaires from the UK in 2025, the largest of any country. The figure was widely quoted and widely challenged, and this year's Henley report dropped numerical migration estimates altogether. → The Sunday Times Rich List 2026 counts 157 UK billionaires, 20 fewer than four years ago. Around one in six families on the 2024 list no longer appear. → 24 of the 350 individuals and families on this year's list now live in Monaco. → At the same time, UBS data suggests the UK's overall millionaire population grew in 2025, as rising asset prices created new millionaires faster than others left. So, for now, the evidence points less to a proven mass exodus of millionaires and more to a potentially significant concentration of departures at the very top: billionaires, top taxpayers and former non-doms, where a small number of individuals account for a disproportionate share of receipts.
What is the cost to the Treasury?
There is no official estimate. The government has acknowledged that HMRC does not hold complete data on taxpayers leaving by income level, and not everyone is required to tell HMRC when they go. The OBR has said it does not have enough evidence to revise its estimate of the migration impact of the non-dom reforms, which assumed a quarter of non-doms with trusts and around 12% of others would leave. High-profile departures do not yet show up fully in the data. The first full self-assessment picture under the new regime is expected next year, and that is when real numbers will start to emerge. With the Autumn Budget next month, timing matters.