Nadhim Zahawi, who aspires to becoming a tax-cutting chancellor, has legitimately used a tax haven for family investments while building a colourful portfolio of outside interests. The Conservative MP for Stratford-upon-Avon, 55, began his new job at the Treasury on Wednesday having previously faced scrutiny over his past dealings with oil companies, medical firms and a tax haven. Before being elected to parliament in 2010, Zahawi was perhaps best known for co-founding the highly successful research firm YouGov, where he was chief executive until February of that year. After he stepped down from YouGov, a company referred to in Companies House documents as “the family trust of the Zahawi family” held £20m of YouGov shares. The Guardian disclosed that the firm, called Balshore Investments, operated from a lawyers’ office in Gibraltar. Another Gibraltar-based firm, Berkford Investments Limited, lent Zahawi money to buy an estate and riding stables, now worth £1m, in the village of Upper Tysoe, near Stratford-upon-Avon. Documents obtained from Companies House in Gibraltar showed that Berkford Investments Limited was managed by T&T Management Services Limited, which shares the same address. T&T Management Services Limited’s website advertises its services as administering trusts for wealthy individuals and families to manage their assets, and avoid or minimise paying property taxes. Once in parliament, Zahawi profited from a second job with Gulf Keystone Petroleum, which paid him £52,325 in backpay in October 2015 and a monthly salary of £20,000 from October 2015, rising to almost £30,000 a month in August 2017, and about £330,000 in bonus payments. He stepped down from the firm when he became a government minister in 2018, at which time he received a final payment of £116,000. He also declared shareholdings in Genel Energy, an Anglo-Turkish oil and gas exploration and production company, and a donation from Amjad Bseisu, the chief executive of the UK-based oil company EnQuest. More recently, after Zahawi was appointed to be the vaccine deployment minister during the Covid pandemic, his wife, Lana Saib, was the director of a medical company, Companies House records show. Saib was listed as the owner, with a 75%-plus shareholding, of a firm called Warren Medical Limited. The company was incorporated on 10 June 2020 under the name “Zahawi Warren Limited”, before being changed a day later to its current title. The two other directors of the company, Ahmad Shanshal and Jaafar Shanshal, are Zahawi and Saib’s sons. Asked about the firm on LBC Radio, Zahawi said it was intended for a property deal that never came to pass and was fully declared to the Department for Business, where he was a minister at the time. “I can tell you very precisely that my wife had looked at a project, a property project to invest in a brain injury rehabilitation centre as a property investment,” he said. Zahawi was made minister for vaccines in November 2020, after serving as a business minister for more than a year. Zahawi, often reported to be one of the wealthiest MPs in parliament, has said his financial interests have been properly declared to both the tax and parliamentary authorities. After taking up the post as chancellor following Rishi Sunak’s resignation, Zahawi told Sky News on Wednesday that he would review tax policies: “I will look at everything. There’s nothing off the table. I want [the UK] to be one of the most competitive countries in the world for investment.” He added: “I know that boards around the world, when they make investment decisions, they’re long-term, and the one tax they can compare globally is corporation tax. I want to make sure that we are as competitive as we can be whilst maintaining fiscal discipline.” A government spokesperson said: “Since first becoming a minister, the chancellor has declared relevant interests and complied with all requirements set out in the ministerial code.”