JPMorgan Chase CEO Jamie Dimon has cautioned the UK's new Prime Minister against implementing tax increases targeting the banking sector.

The head of the major financial institution stated that such a move would jeopardize the bank's planned £3 billion investment in a new London office complex and could have numerous adverse effects on the UK's investment climate.

Shortly after former Greater Manchester Mayor Andy Burnham succeeded Sir Keir Starmer as Prime Minister on Monday, Dimon, who leads the world's largest bank, urged the new leader not to view the City of London as an easy target for generating additional tax revenue.

Addressing the risk of Burnham potentially raising the bank levy or the corporation tax surcharge, Dimon remarked that this "would be another negative factor to weigh." These taxes were established following the UK government's bailout of major domestic banks during the 2008 financial crisis.

Speaking on a television program, Dimon said, "Saying 'let's tax banks' sounds great, but that extra tax ultimately comes from our shareholders, amounting to $5 billion. I've always believed such policies have negative consequences."

Last year, after the UK government pledged to maintain pro-business policies, Dimon approved JPMorgan Chase's plans for a new 3 million square foot London headquarters. He praised outgoing Chancellor Rachel Reeves in a podcast for doing "a great job," noting that former Defence Secretary John Healey assumed her role on Monday evening.

Regarding the new London office plans, the American banking executive stated that if the Burnham government insists on increasing the tax burden on banks, he is uncertain what subsequent actions JPMorgan Chase might take. He also warned, "If I were a government, I would never think that deliberately increasing the tax burden on specific companies is beneficial for the country's development."

On the UK bank levy, Dimon commented, "I've always thought this tax itself is unreasonable. JPMorgan Chase has never caused losses for the UK. Back then, I specifically called the then Chancellor. We are rooted in the UK, operate compliantly, employ a large number of local staff, and also hope to continue expanding our business presence here."

These remarks represent Dimon's latest move to exert pressure on UK political circles. He is currently also facing questioning from US Congress senators regarding whether he followed advice from the late sex offender Jeffrey Epstein in 2009 to lobby the UK government to abolish the bank executive bonus tax.

The current corporation tax rate for UK banks is 28%, higher than the standard 25% rate for ordinary companies. In addition, banks must separately pay a bank levy based on their UK balance sheets.

Dimon, who has led JPMorgan Chase since 2006, said in the podcast, "When a tax system loses competitiveness, capital flows out. Capital leaving the country will flow to other nations, and the current situation has already confirmed this. In recent years, many companies have delisted from the London Stock Exchange. If I were leading a country, I would absolutely not want to see this scenario."

Various trade unions have been calling on Burnham to implement wealth tax reforms, including aligning capital gains tax with income tax rates and increasing the tax burden on the banking sector.

Paul Nowak, General Secretary of the Trades Union Congress, suggested that by reversing the bank surcharge cuts implemented by the previous Conservative government, the Burnham administration could raise an additional £9 billion over four years.

Some within the finance industry worry that the new Prime Minister, to appease the moderate left-wing faction of the Labour Party and fund new investments in public services, is highly likely to adopt such tax increase proposals.