In the Partygate scandal it was found that multiple parties had been held at 10 Downing Street during national COVID-19 lockdowns, and COVID-19 social distancing laws were breached by 83 individuals, including Sunak, who in April 2022 was issued with a fixed penalty notice.

In the weeks leading up to Johnson's first cabinet reshuffle in February 2020, a number of briefings in the press had suggested that a new economic ministry led by Sunak might be established, to reduce the power and political influence of the Treasury.

During the meeting, Johnson had offered to allow Javid to keep his position on the condition that he dismiss all his advisers at the Treasury and replace them with ones selected by 10 Downing Street.

[9][10] Some political commentators saw Sunak's appointment as signalling the end of the Treasury's independence from Downing Street, which began during Gordon Brown's chancellorship under Tony Blair, with Robert Shrimsley, chief political commentator of the Financial Times, arguing that "good government often depends on senior ministers – and the Chancellor in particular – being able to fight bad ideas".

[13] On 23 March 2020, as COVID-19 had become a pandemic and began rapidly spreading across the country, Johnson announced the first national lockdown and Parliament introduced the Coronavirus Act 2020, which granted the devolved governments emergency powers and empowered the police to enforce public health measures.

Across the country, localised lockdowns, social distancing measures, self-isolation laws for those exposed to the virus and rules on face masks were introduced, as well as efforts to expand COVID-19 testing and tracing.

It also forwent the procurement process in contracts in response to shortages of PPE and medical equipment, major issues in the early months of the outbreak, and for developing a contact tracing app.

[20][21] The UK government's response to the pandemic, in particular the timeliness of public health measures being introduced and lifted, has faced criticism from academic medical sources, media outlets, relatives of COVID-19 patients and various political figures.

[22] Sunak said he had opposed recommendations by government medical advisers for a second "circuit-breaker" lockdown in September 2020 due to the potential impact on jobs and the economy.

[23] According to the diary of Vallance, he was told by Dominic Cummings, Johnson's chief political adviser, that Sunak had argued to "just let people die" during an argument over imposing a second lockdown in October 2020.

The decision to extend the job retention scheme was made to avoid or defer mass redundancies, company bankruptcies and potential unemployment levels not seen since the 1930s.

They called for publication of the names of companies receiving Bounce Back Loans to enable data matching to prevent, deter and detect fraud.

[57] In December 2020, it was reported that banks and the National Crime Agency also had concerns about fraudulent abuse of the Bounce Back Loan Scheme.

[58] In January 2021, the NCA reported that three city workers who worked for the same London financial institution had been arrested as part of an investigation into fraudulent Bounce Back Loans totalling £6 million.

In April 2022, amid the Partygate scandal, Sunak was issued a fixed penalty notice by the police who found he had committed offences under COVID-19 regulations by attending a birthday party for Johnson on 19 June 2020.

[64] ITV News later reported that some of Sunak's junior aides at the time suggested he should resign in order to challenge Johnson's leadership, but he chose not to.

[73] During the speech he gave on 3 November, he said that he felt optimism despite daunting challenges and that by bringing together finance ministers, businesses and investors, COP 26 could begin to deliver targets from the Paris Agreement.

He announced support for a new Capital Markets Mechanism which will issue green bonds in the U.K. to fund renewable energy in developing countries.

[74] Sunak privately lobbied to impose a green levy, which would have led to higher petrol and diesel prices, to help pay for the plan to reduce greenhouse gas emissions to net zero by 2050.

[76][77] In April 2022, Sunak ordered the Royal Mint to create a UK government-backed non-fungible token (NFT) to be issued by summer 2022.

[84][85] In early 2022, newspapers reported that Murty had non-domiciled status, meaning she did not have to pay tax on income earned abroad while living in the UK.

[86][87] Following media controversy, Murty stated on 8 April that she would pay UK taxes on her global income, adding in a statement that she did not want the issue "to be a distraction for my husband".

[88] Reporting around this time also revealed that Sunak had continued to hold United States' permanent resident (green card) status he had acquired in the 2000s until 2021, including for 18 months after he was made chancellor, which required filing annual US tax returns.

Concerns were subsequently raised by organisations including HM Revenue and Customs and the Institute for Fiscal Studies about the statement's impact, as well as its cost-effectiveness, while at least one major retailer declined to take advantage of a financial bonus scheme intended for rehiring employees placed on furlough during the pandemic.The Winter Economy Plan was delivered by Sunak on 24 September 2020.

[96] In October 2021, Sunak made his third and final budget statement, which included substantial spending promises to a large extent related to science and education.

He cut fuel duty, removed VAT on energy saving equipment (such as solar panels and insulation) and reduced national insurance payments for small businesses and, while continuing with a planned national insurance rise in April, he promised to align the primary threshold with the basic personal income allowance as of July.

For me to step down as Chancellor while the world is suffering the economic consequences of the pandemic, the war in Ukraine and other serious challenges is a decision that I have not taken lightly.

We both want a low-tax, high-growth economy, and world class public services, but this can only be responsibly delivered if we are prepared to work hard, make sacrifices and take difficult decisions.

[105] In the early stages of the COVID-19 pandemic, he was popular by the standards of British politics, described by one analyst as having "better ratings than any politician since the heydays of Tony Blair".

[107][108][109] In an Ipsos MORI poll in September 2020, Sunak had the highest satisfaction score of any British chancellor since Labour's Denis Healey in April 1978, and was widely seen as the favourite to become the Conservative leader after Boris Johnson.