The Treasury has launched an investigation into how details of a bank tax rise were reported in the media before Chancellor John Healey announced them in his Budget on 28 October 2026. The inquiry is being led by the Government Security Group in the Cabinet Office, according to a letter from the Treasury's top civil servant, James Bowler, published by Parliament's Treasury Committee on Tuesday 10 November.

Hours before Healey's Budget, Bloomberg reported at 10.45am that it would contain a temporary bank tax increase of less than 8%, lower than lenders had feared. Bank shares rose after the report. Healey later announced that the bank corporation tax surcharge would rise from 3% to 6% for 15 months, from 1 January 2027 to 31 March 2028. Bowler said he had been assured that no banks, their representatives or trade bodies were briefed on the changes before the Chancellor's statement.

Chancellor to face MPs on Wednesday

Treasury Committee chair Dame Meg Hillier said she suspected the inquiry would find no evidence of a breach, but that she would press Healey for answers when he appears before the committee on Wednesday 11 November for a session on his Budget. The committee had also asked the FCA to assess whether the incident could amount to an improper release of inside information, and the regulator said on 3 November that it would work with the Treasury and Cabinet Office and consider whether action under market abuse rules was appropriate.

Confirmation of the investigation does not establish that an unlawful disclosure took place or that anyone traded improperly. Healey has sought to tighten Treasury security since last year's Budget, and the leak inquiry is a setback for the Chancellor as he defends his first Budget before MPs.