UK Budget Leak Investigation Launched After Bank Tax Details Surfaced Before Chancellor’s Speech

Britain’s Government Security Group has started an investigation into a potential leak of Budget measures which may have moved financial markets, the Treasury Committee said in a statement on Tuesday 10 November 2026. The UK budget leak investigation follows concerns that details of changes to bank taxes reached the press before Chancellor John Healey delivered his Budget speech on Wednesday 28 October 2026. Reuters reported the launch of the inquiry on Tuesday afternoon, citing the committee’s statement.

The inquiry centres on a Bloomberg report published almost two hours before Healey spoke. That report said the planned increase in the bank corporation tax surcharge would not return it to the previous 8% level and would be temporary. When Healey delivered the Budget, he raised the surcharge to 6%, rather than 8%, for 15 months from January 2027. The match between the early report and the announced policy is what turned a timing question into a formal investigation.

UK Budget Leak Investigation — Quick Reference Summary

The Bloomberg report that started the scrutiny

The Treasury Committee’s concern began with timing. A Bloomberg article published on the morning of Wednesday 28 October 2026, almost two hours before Healey’s speech, reported that the planned increase in the bank corporation tax surcharge would not take it back to 8%. The article quoted “people familiar with the matter” and said any increase would be temporary.

Committee chair Dame Meg Hillier raised the matter the next day, Thursday 29 October 2026. In letters to HM Treasury permanent secretary James Bowler and FCA chief executive Nikhil Rathi, she said the report appeared to be “more than idle speculation” and that it had “implications for relevant securities”. Her letters asked for cooperation between the Treasury and the FCA in establishing how the details emerged.

Hillier also asked Bowler to confirm whether banks, or their representatives or trade bodies, had been told of the changes in outline or in detail before the Budget and the Chancellor’s statement. That question goes to the heart of the inquiry, because advance notice given to one group and not the market would raise serious fairness issues.

What the Chancellor actually announced on bank tax

Healey’s Budget on 28 October 2026 raised the bank corporation tax surcharge to 6%, rather than the 8% rate many in the City had expected. The increase runs for 15 months from January 2027. Our UK Budget 2026 preview set out what Healey was expected to announce before he spoke, including the tight fiscal backdrop he faced.

The surcharge was only one part of a wide-ranging statement. The same Budget brought changes that are still being digested, including the pension inheritance tax changes that take effect on 6 April 2027. The bank tax detail, however, is the one that moved first in the markets, because a lower-than-expected surcharge is good news for bank earnings and share prices.

That market sensitivity is why the timing matters so much. Budget measures are among the most closely guarded secrets in British government, and the Chancellor’s speech is meant to be the moment the market first hears them. A report published hours early, if based on a genuine leak, would hand its readers a trading advantage over everyone else.

How the Treasury Committee and the FCA responded

The FCA responded to Hillier’s letter on Tuesday 3 November 2026. Chief executive Nikhil Rathi said the Treasury and the Cabinet Office would be “best placed to ascertain and determine whether and how any unlawful disclosure of inside information may have occurred”. The regulator said it would engage with them and consider any evidence they provided.

Rathi added that the FCA “stands ready” to consider the specifics of any evidence from the Cabinet Office and HM Treasury and decide what action, if any, it should take under the market abuse rules. The Press Association reported his response on 3 November 2026, and the same account was carried by several regional newspapers.

The Treasury Committee kept up the pressure in parallel. Hillier’s letters called for cooperation between the Treasury and the FCA in considering how the event occurred, what steps were needed to find out who was responsible, and whether action was required to prevent a repeat. The committee’s statement on Tuesday 10 November 2026, announcing that the Government Security Group had begun its investigation, is the first concrete step to have been made public since then.

Why a pre-Budget leak matters for markets

Budget secrecy exists for a practical reason, not just tradition. Tax changes move share prices, and anyone who knows them in advance can trade on that knowledge before the rest of the market. The FCA’s own framework treats the unlawful disclosure of inside information as market abuse, which is why Rathi pointed to the market abuse rules in his reply.

In this case, the concern is specific. Bank shares appeared to rise after the Bloomberg report suggested a softer surcharge than expected, and Hillier told the FCA the report had “implications for relevant securities”. No figure for any share-price movement has been published by the committee, and no trader or official has been named in connection with the leak.

The episode also lands in a wider debate about Budget discipline. Healey’s statement was his first as Chancellor, delivered under Prime Minister Andy Burnham, and it arrived against a backdrop of rising inflation and borrowing costs. A leak inquiry in the first weeks of a new chancellorship is an unwelcome distraction, and the Government will want the investigation to be quick and conclusive.

What happens next in the UK budget leak investigation

The Government Security Group will now examine how the surcharge details reached Bloomberg before the speech. Its work is separate from the FCA’s role, which is to judge whether any disclosure amounted to unlawful inside information and whether enforcement action is warranted. Neither body has given a timetable, and neither has said who was interviewed or what documents were examined.

Three questions will shape the outcome. The first is whether the information came from inside government or from a bank or trade body briefed in advance. The second is whether anyone traded on it. The third is what changes to Budget security follow, since Hillier has already asked what steps are needed to prevent a repeat.

Until the investigation reports, the leak remains potential rather than proven. The committee has not alleged that any named individual disclosed the information, and the FCA has not opened an enforcement case. What is certain is that the inquiry is now formal, public, and being watched by the City, Parliament, and the Treasury itself. Reuters reported the launch of the UK budget leak investigation on 10 November 2026, and the Press Association set out the FCA’s position in its 3 November 2026 report.

Questions readers are asking about the UK budget leak investigation

Q: What is the UK budget leak investigation?
A: It is an inquiry by Britain’s Government Security Group into a potential leak of Budget measures which may have moved financial markets. The Treasury Committee announced it in a statement on Tuesday 10 November 2026.

Q: What was leaked before the Budget?
A: A Bloomberg report published almost two hours before Chancellor John Healey’s speech on 28 October 2026 said the bank corporation tax surcharge would stay below the expected 8% and that any rise would be temporary. Healey then raised the surcharge to 6% for 15 months from January 2027.

Q: Who raised the alarm about the leak?
A: Dame Meg Hillier, chair of the Treasury Committee. She wrote on 29 October 2026 to HM Treasury permanent secretary James Bowler and FCA chief executive Nikhil Rathi, saying the report appeared to be “more than idle speculation” with “implications for relevant securities”.

Q: What has the FCA said about the budget leak?
A: On 3 November 2026, chief executive Nikhil Rathi said the Treasury and Cabinet Office were best placed to determine whether any unlawful disclosure of inside information occurred. He said the FCA “stands ready” to consider any evidence and decide on action under the market abuse rules.

Q: Has anyone been accused of leaking the Budget?
A: No. No person has been named or accused, and no finding has been made. The leak is described by the Treasury Committee as potential, and the investigation is at an early stage.

Q: Why does a leak before the Budget matter?
A: Budget tax changes move share prices. Anyone who learns them early could trade before the rest of the market, which is why the unlawful disclosure of inside information can amount to market abuse.

Myth-busting: the UK budget leak

• Myth: The leak has been proven and someone has been caught. Reality: no finding has been made. The Treasury Committee describes a potential leak, and the Government Security Group investigation has only just begun.
• Myth: The whole Budget was published before Healey spoke. Reality: only the bank surcharge detail was reported early, in a single Bloomberg article. The rest of the Budget was announced in the speech as planned.
• Myth: The FCA has opened an enforcement case. Reality: the FCA said on 3 November 2026 that it “stands ready” to act on evidence from the Treasury and Cabinet Office. It has not announced enforcement action.
• Myth: Bank shares definitely rose because of the leak. Reality: the committee said the early report had “implications for relevant securities” and bank shares appeared to rise. No causal finding or figure has been published.