The number of British millionaires has fallen to its lowest level in nearly two decades, with high taxes under the Labour government and persistent inflation being blamed. Last November, the country’s business secretary said he was worried that billionaires, entrepreneurs, and even doctors were leaving because of Rachel Reeves’ budget. Now, those concerns are resurfacing as the U.K.’s new prime minister, Andy Burnham, considers a 2% tax on wealth above £10 million ($13.3 million).

The trend is already visible, according to Martin Ott, the CEO of Taxfix, the Berlin-based tax app valued at more than $1 billion. Ott told Fortune exclusively that some wealthy U.K.-based clients have been considering moving abroad to reduce their tax bills, although he does not support that choice.

“Yes, there are certain customers, at a certain income bracket, that are moving to save money abroad,” said Ott, a former Meta executive. “I always encourage people to stay where you are.”

‘You have a social responsibility to invest in your country’

In 2025, more millionaires left the U.K. than any other nation. According to the Henley Private Wealth Migration Report 2025, about 16,500 millionaires relocated last year, taking roughly $91.8 billion with them. Over the past decade, that has translated into a 9% decline in the U.K.’s millionaire population, driven in part by Brexit-related fallout, political uncertainty, and tax changes.

Ott said leaving now would be short-sighted. If the country’s top founders and highest earners depart, he argued, the ecosystem that helped them succeed would weaken, affecting the broader base of people who build and work in it.

“Saving taxes is one thing, but at the same time, you also have a social responsibility to make sure you invest in a country,” he said.

In Ott’s view, wealth brings an obligation to help preserve a healthy environment for the next generation of builders, operators, and workers. He said many of his friends and peers—people who could easily move to Dubai or Montenegro—are choosing to remain in place.

“They’re saying, we’re not moving…We really want to make sure we also give back and build cool stuff that makes it worthwhile staying,” he said.

Ott added that the more responsible approach is to stay through the cycle, keep building, and strengthen the system from within. “You don’t want a brain drain…I can only just encourage everyone to stay, build great new businesses, create an environment where entrepreneurs want to start something,” he said.

‘Plus, pressure creates diamonds’

Reflecting on his early fintech career in London during the financial crisis, Ott recalled managing hundreds of millions of customers’ money in bank accounts while not knowing whether the banks would survive the next day. He said that period left a lasting lesson about working through instability rather than assuming it will remain permanent.

“There was also that feeling that the world is going down. Do we need to move somewhere else? No, everything goes in phases,” Ott said.

He said the crisis taught him “what it means to go through crisis,” including how to manage his own health and how to be a better manager when conditions are difficult. More importantly, he said it showed him that downturns do not last forever.

“Taking a more balanced, long-term view—that’s what I learned,” he said. “Things aren’t as bad as they look in the moment.

“And then new opportunities are born, and you can deal with crisis, because it’s constant, you’ll always have stuff that’s getting thrown your way.”

A version of this story originally published on Fortune.com on November 25, 2025.

Read more on wealth from Fortune’s Orianna Rosa Royle:

• How Montenegro became the world’s fastest-growing hub for millionaires
• This millennial became a millionaire before turning 30 thanks to early investments in Deliveroo and Revolut—he shares how Gen Z can spot the next startup jackpot
• This millennial went from being a builder on $5 an hour to launching (and selling) Wingstop UK for $532 million—with zero restaurant experience
• A 2-year taste of the office was enough to make 3 grads quit. Now they run a $13.2 billion investment firm: ‘We didn’t want a traditional job again’
• A Gen Xer sold his company for $1.6 billion. He kept less than $100 million and gave the rest away because he doesn’t ‘believe in billionaires’

This story was originally featured on Fortune.com