The Princess of Wales will not attend a rehearsal for Trooping the Colour, HELLO! understands.
The Colonel's Review is set to take place in London on 8 June, and as Colonel-in-Chief of the Irish Guards, Kate would usually take the salute.
However, Lieutenant General James Bucknall, KCB, CBE, will carry out the role of Inspecting Officer on behalf of the Princess as she continues her recovery.
Kate announced back on 22 March in an emotional video message that she is undergoing preventative chemotherapy following a cancer diagnosis. Watch it here in full...
But just weeks before her illness was made public and amid her recovery from major abdominal surgery, the army was forced to remove an announcement on its website that the Princess would be conducting the review after not seeking approval from Kensington Palace.
Tickets were being sold on the official website for the military spectacle, advertising an appearance by Kate.
The announcement caused confusion at the time because there had been no official confirmation from the palace.
Kate's last official public appearance was on Christmas Day 2023 as she and Prince William walked to church with their three children, Prince George, Princess Charlotte and Prince Louis.
It comes as Buckingham Palace confirmed that the King will participate in his birthday parade – known as Trooping the Colour – on 15 June.
Charles, 75, who is also being treated for an undisclosed form of cancer, will inspect the soldiers during the ceremony from a carriage with Queen Camilla by his side.
It has not been confirmed which members of the royal family will join the King and Queen at the parade, but in recent years only working royals have participated and watched the flypast from the Buckingham Palace balcony.
When will Kate return to royal duties?
While the Princess' return to her public duties has not been announced by Kensington Palace, she has been spotted out and about in recent weeks while undergoing treatment, HELLO! understands.
It comes after Kate was said to be "excited" by her business taskforce's new report that claims the UK could reap £45.5 billion in economic benefits if firms prioritise early childhood.
A Kensington Palace spokesperson said earlier this month: "Early childhood is a huge priority for the Princess of Wales and she has been kept fully up to date throughout the process and the development of the taskforce's work, and she has seen the report."
However, royal sources told HELLO! this did not signify a return to royal duties for Kate who "needs the space and privacy to recover" and will not go back to work until her medical team gives her the green light.