Treasury chief secretary Chris Philp has been moved to the Cabinet Office following the sacking of Chancellor Kwasi Kwarteng.
Liz Truss is seeking to get her embattled fledgling government back on track following the market turmoil unleashed by the mini-budget.
Economic chaos was triggered after the government last month announced a £45bn package of unfunded tax cuts alongside a commitment to an energy price guarantee for the next two years.
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The Treasury clear-out comes as the prime minister announced corporation tax would increase in a second major U-turn after promising not to hike it in the recent fiscal statement.
Former foreign secretary Jeremy Hunt has been appointed as Mr Kwarteng’s replacement, while Mr Philp is replaced by Edward Argar.
The Tory MP swaps jobs with his party colleague as paymaster general and minister for the Cabinet Office.
His change in job will widely be seen as a demotion.
Mr Philp is understood to have been the leading advocate of the controversial move to scrap the 45p tax rate for highest earners, which was reversed in a dramatic climbdown at the recent Conservative Party conference.
He faced mockery by opponents at Westminster earlier this week after he insisted the government was not planning any further rowing back on tax measures, leading to shouts of “yet” by Labour MPs in response.