Rishi Sunak is being investigated by parliament’s commissioner for standards over a potential breach of the rules for MPs. Here is what we know about the case. What is the investigation about? The website of the commissioner, Daniel Greenberg, says only that it relates to the requirement for MPs to be “open and frank in declaring any relevant interest in any proceeding of the house or its committees”. However, No 10 has confirmed it relates to his links to a childcare firm in which his wife is an investor. Akshata Murty, is listed as a shareholder in Koru Kids, which is among the private childcare providers likely to benefit from a pilot scheme proposed in last month’s budget to train new childminders. How did the alleged breach happen? A fortnight after the budget, Sunak was answering questions before the liaison committee, the super-committee of senior MPs. The Labour MP Catherine McKinnell asked the prime minister if he had anything to declare in relation to the choice of the six providers. Sunak replied: “No, all my disclosures are declared in the normal way.” It later emerged that executives from Koru Kids attended a Downing Street reception hours after the committee appearance. What is the alleged wrongdoing? The commissioner will examine whether Sunak should have declared his wife’s shareholding to McKinnell, and also whether he should have listed it on the register of MPs’ interests, which is updated every fortnight. What is Downing Street’s defence? The No 10 line, explained when the alleged lack of transparency first emerged before Easter, is that Sunak had declared the investment to the separate register of ministers’ interests, and thus did not need to cite it in the MPs’ register, or to the committee. However, the ministerial register has not been updated for nearly a year, and so Sunak’s declaration about Koru Kids is not yet public. The ministerial register is supposed to be published twice a year, but has been delayed as the post of adviser on ministerial interests, which oversees it, was empty for six months. The previous holder, Christopher Geidt, stepped down in June amid his unhappiness about Boris Johnson’s role in lockdown-breaching No 10 parties. His successor, Laurie Magnus, took over in December. What happens next? Greenberg will now investigate the allegations, a process that can take months to complete. His decision, and a recommendation for any possible punishment, would then be passed to the standards committee, which combines MPs and lay members, who oversee the commissioner’s work. Sunak could speed up the process by agreeing to what is known as rectification, in which MPs agree to correct the register of interests. This, however, would require him to agree that his stated interpretation of the rules had been incorrect. Could Sunak be punished? In theory, yes, as failure to register interests breaches the code of conduct for MPs. This is generally seen as one of the lesser issues examined by the commissioner. However, the fact that Sunak did not simply omit to mention an interest but told McKinnell he did not have an interest could make this more serious. Is this Sunak’s first brush with rule-breaking? It is not. When he was Boris Johnson’s chancellor, Sunak was fined along with Johnson for attending the then-PM’s birthday party inside No 10 in June 2020, in breach of Covid laws in place at the time. In January, Sunak became the second prime minister to be fined while in office, receiving a fixed-penalty notice for not wearing his seatbelt while filming a social media video and travelling in the back of a car.