John Healey ordered Treasury officials to calculate what pre-Budget speculation on taxes and spending costs the economy and people's decisions, City AM reports. It says the order came after he became Chancellor.
City AM says Healey has tended to tell reporters that speculation has real-world impacts.
The paper also says Healey has brought in unprecedented security measures to stop Budget leaks, borrowed from his time at the Ministry of Defence. Citing the Financial Times, it says these include changing software settings and limiting how many people can access documents.
According to City AM, the Budget date of Wednesday 28 October is a month earlier than last year's and was meant to squash the rumour mill.
The Treasury has not confirmed any of this, and it has not been independently checked. Reported Budget measures remain unconfirmed until they appear in the statement or are confirmed by the Treasury.