An official investigation has been launched into the possible disclosure of market-sensitive Budget information before Chancellor John Healey announced changes to taxes on banks, following concerns raised by MPs about movements in financial markets.
The investigation was confirmed on Tuesday 10 November 2026 in correspondence published by the House of Commons Treasury Committee. James Bowler, Permanent Secretary at HM Treasury, confirmed that the Cabinet Office’s Government Security Group is leading the inquiry, with assistance from Treasury officials.
The investigation follows concerns that details of changes to the Bank Corporation Tax Surcharge appeared in financial reporting before the Chancellor formally announced the measures to Parliament on 28 October. There has been no finding that confidential information was unlawfully disclosed or that any individual engaged in improper trading.
What Information Appeared Before the Budget?
The concerns centre on advance reporting about the Government’s plans to increase the Bank Corporation Tax Surcharge. A Bloomberg report published at approximately 10.45am on Budget day indicated that the proposed increase would be less severe than some banks had feared and would apply temporarily.
When the Chancellor subsequently delivered his Budget statement, he confirmed that the surcharge would rise from 3% to 6% for a 15-month period beginning on 1 January 2027. The measure was presented as part of plans to fund support for households facing cost-of-living pressures.
Treasury Committee chair Dame Meg Hillier questioned whether movements in bank share prices before the Budget could have been influenced by the advance information. The timing and content of the reporting prompted parliamentary scrutiny, but do not themselves establish that a prohibited disclosure occurred.
Treasury Confirms Cabinet Office Investigation
In a letter published by the Treasury Committee, Bowler confirmed that the Government Security Group within the Cabinet Office is leading an investigation, supported by HM Treasury. He said he would not prejudge its findings.
Bowler said he had received assurances that banks, their representatives and trade bodies had not been briefed on the details of the Bank Corporation Tax Surcharge changes before the Chancellor’s announcement. That assurance does not amount to a completed investigation into every possible source of the information.
Treasury Defends Its Security Arrangements
Bowler said the Treasury had strengthened information security arrangements following an earlier review, including tighter digital access controls, encryption and restrictions on printing, downloading and forwarding sensitive documents.
He acknowledged that the number of people requiring access to Budget information necessarily increases as officials prepare for the Chancellor’s statement, while maintaining that those involved remain subject to strict confidentiality requirements.
Treasury Committee Chair Demands Answers
Dame Meg Hillier criticised the recurring pattern of investigations into possible Budget leaks that do not identify wrongdoing while promising stronger safeguards. She said MPs still needed answers about how potentially market-sensitive information was circulating among journalists before being announced to Parliament.
Hillier has indicated that she intends to raise the matter directly with the Chancellor when he appears before the Treasury Committee on Wednesday 11 November.
Financial Conduct Authority Also Examining Concerns
The Treasury Committee previously wrote to the Financial Conduct Authority asking whether the circumstances raised issues under market abuse rules. FCA chief executive Nikhil Rathi responded that the Treasury and Cabinet Office were best placed to establish whether an unlawful disclosure occurred.
The regulator said it would consider relevant evidence and determine whether action under market abuse rules was appropriate. This is not a finding that market abuse occurred or confirmation that enforcement proceedings have begun.
Why Does a Possible Budget Leak Matter?
Budget announcements can affect the prices of shares, bonds and other financial instruments. Changes to bank taxation are particularly relevant to investors assessing the future profitability of financial institutions.
If market-sensitive information becomes available to selected individuals before formal announcement, questions can arise about fairness and market integrity. But prices can also move in response to speculation, expectations and legitimate reporting. Establishing an improper disclosure requires evidence beyond the timing of reporting and subsequent market movements.
Chancellor Faces Questions on Wednesday
The Treasury Committee is scheduled to question Chancellor John Healey on Wednesday 11 November as part of its scrutiny of the Autumn Budget. The public hearing is scheduled to begin at 2.15pm.
For now, the confirmed development is an official investigation into a suspected disclosure. Its findings, and any subsequent regulatory or disciplinary action, remain outstanding.