Mrs Johnson had in the past dismissed claims she had held parties in her Downing Street flat.
“In the interests of transparency,” a spokesperson for Mrs Johnson confirmed that the former director of communications for the Tories will be receiving a fixed penalty notice (FPN) alongside her husband, Boris Johnson, and Chancellor Rishi Sunak.
Mrs Johnson had in the past dismissed claims she had held parties in her Downing Street flat as “total nonsense”.
The spokesperson said: “In the interests of transparency, Mrs Johnson can confirm she has been notified that she will receive a fixed-penalty notice.
“She has not yet received any further details about the nature of the FPN.”
Scotland Yard told the Prime Minister his fine relates to an event in the Cabinet Room on his birthday in June 2020 but did not say whether Mrs Johnson’s fine relates to the same gathering.
The Met is investigating alleged Covid law-breaking at 12 gatherings in Whitehall and Downing Street and Mrs Johnson has been linked to two events.
Downing Street admitted staff “gathered briefly” in the Cabinet Room on June 19 2020, in what was reportedly a surprise get-together for the Prime Minister organised by Mrs Johnson.
The PA news agency was told Lulu Lytle, the interior designer behind lavish renovations of the Downing Street flat, briefly attended while undertaking work there.
However, No 10 has denied a report that, later the same evening, family and friends were hosted upstairs to celebrate the occasion.
Mrs Johnson also reportedly hosted parties in the official flat over No 11 where she and her husband live, including one event on November 13, the night of Dominic Cummings’ acrimonious departure.
A spokesman for the Prime Minister’s wife called the claim “total nonsense”.
However, reports have since suggested that the Prime Minister was seen heading up to the flat on the night in question, with The Mail On Sunday stating that Abba songs, including The Winner Takes It All, were heard coming from the residence.
Mr Cummings, former de facto chief-of-staff at No 10, has alleged there are photographs of parties held at the flat during lockdown and said he has spoken to people who heard music coming from the Johnsons’ accommodation on the night he left Downing Street.
On Tuesday, Scotland Yard announced it had made at least 50 referrals for fixed-penalty notices, up from 20 at the end of March, to ACRO Criminal Records Office, which is responsible for issuing the fines.
Labour leader Sir Keir Starmer had called for Mrs Johnson to be named if issued with a fixed-penalty notice.
Speaking to broadcasters in Bury at the end of March, the Labour Party leader said: “If Carrie Johnson gets a fixed penalty notice, then of course it should be made public.
“My focus is on the Prime Minister because he is the one who sets the culture, he is the one who oversaw this criminality at his home and his office, he is the one that came to Parliament and said all rules were complied with, which is clearly not the case.
“So I do think Carrie Johnson should be named if she gets a penalty notice, but my focus is laser-like on the Prime Minister.”