HMRC became involved after an undercover investigation into Mr Zahawi’s finances was launched by the National Crime Agency (NCA) in 2020. The Independent has also learned that officers from the Serious Fraud Office (SFO) investigated the chancellor’s financial affairs. The investigation then passed to HMRC, which comes under the control of the Treasury – the department Mr Zahawi now heads. A senior Whitehall source confirmed that the tax investigation is currently unresolved. It can also be revealed that Boris Johnson, Home Secretary Priti Patel and the Cabinet Office have been briefed on the investigations. The revelations come as multi-millionaire Mr Zahawi announced he is entering the leadership race to succeed Johnson as prime minister. Launching his campaign on Saturday afternoon, Mr Zahawi pledged to cut taxes for individuals, families and businesses, boost defense spending and continue education reforms. The Independent reported on Wednesday that the NCA’s International Corruption Unit was looking into Mr Zahawi’s finances and taxation in an investigation codenamed “Operation Catalufa”. Nadhim Zahawi has publicly called on Boris Johnson to resign two days into his new role as chancellor (Anadolu/Getty) We also described how Mr Zahawi said he knew nothing about the matter until contacted by The Independent. The investigation began in 2020, the year Mr Zahawi rose to political prominence as vaccine minister during the pandemic. There is no indication of any wrongdoing by Mr Zahawi, a popular and respected figure among Tory MPs. Well-placed sources have now confirmed that HMRC, the NCA and the SFO were involved in a “detailed investigation” into Mr Zahawi. It is understood that HMRC’s investigation is being carried out by a unit responsible for offshore tax matters. A Cabinet Office spokesman said: “Under the ministerial code, ministers must ensure that no conflict arises, or could reasonably be perceived to arise, between their ministerial position and their private interests, financial or otherwise ». The spokesman added: “The chancellor followed the process set out in the ministerial code and complied with these requirements to the satisfaction of previous [Whitehall] independent [ethics] advisers”. Mr Zahawi made his fortune with polling firm YouGov and in the oil industry (AFP/Getty) Asked which ethics advisers had cleared Mr Zahawi’s appointment – ​​bearing in mind that Whitehall ethics adviser Lord Geidt resigned last month after falling out with Mr Johnson and has not yet been replaced – the spokesman said they believed Mr Zahawi had been overruled by Lord Geidt’s predecessor, Sir. Alex Allan when Mr Zahawi first became minister in 2018. That was two years before the investigation into Mr Zahawi’s tax affairs began. After the latest revelations were published, a spokesman for Mr Zahawi said: “All of Mr Zahawi’s financial interests have been properly and transparently declared. Mr Zahawi is not aware of any formal investigation by HMRC. His taxes are fully paid and up to date. He will provide full information to any questions HMRC have about his tax affairs.” A Downing Street spokesman said: “The usual pre-appointment declarations have been made by the minister and the necessary checks have been completed.” Mr Zahawi, who moved to the UK from Iraq as a child, made his fortune with polling firm YouGov and in the oil industry, serving as an executive at Gulf Keystone Petroleum until 2018. He became MP for Stratford-upon-Avon in 2010. The former education secretary was appointed chancellor this week after Rishi Sunak resigned. Having defended the prime minister, he then called on him to resign the day after taking up the role, telling Johnson he “must do the right thing and go”. Asked if it had investigated Mr Zahawi, an HMRC spokesman said: “We do not comment on taxpayers who can be identified.” An NCA spokesman said: “The NCA does not confirm or deny the existence of investigations.” An SFO spokesman said they “could neither confirm nor deny” whether it had investigated Mr Zahawi.