The precise sum the King provides to his brother remains undisclosed
Palace officials have confirmed that financial support provided by King Charles to his brother, Andrew Mountbatten-Windsor, cannot be deducted as an official expense for tax purposes.
The payments made to fund Mr Mountbatten-Windsor's lifestyle are not factored into the King's HMRC calculations, officials told The Times, following questions about the tax arrangements.
As a non-working member of the Royal Family, Mr Mountbatten-Windsor's financial support comes entirely from the King's private resources after taxation has already been applied.
The same arrangement applies to funding provided for other non-working relatives, with only expenses incurred by working royals in official capacities qualifying for deductions.
The precise sum the King provides to his brother remains undisclosed, though it is understood to be substantial enough to cover security arrangements, a personal valet and a chef.
Additionally, the sovereign pays rental costs for accommodation occupied by Mr Mountbatten-Windsor's daughters, with Princess Beatrice residing at St James's Palace and Princess Eugenie at Kensington Palace.
Mr Mountbatten-Windsor withdrew from official royal duties in 2019 amid scrutiny over his association with Jeffrey Epstein.
The King subsequently stripped his brother of his royal titles, including Prince and Duke of York, in 2025.
The Palace pointed to the Memorandum of Understanding on Royal Taxation, a Treasury document revised in 2023 following the change of reign, which sets out permissible deductions from the monarch's income.
Allowable expenses include staff-related payments, accountancy fees, medical insurance, and official gifts such as "donations, cups, prizes, flowers and presents" given in the King's capacity as sovereign.
Maintenance costs for Balmoral, Sandringham and other private residences may be partially deducted where they relate to official use, along with uniforms for working royals but not other clothing.
The late Queen Elizabeth II first consented to paying income tax in 1993, following the Windsor Castle fire the previous year.
The King has made history by becoming the first British monarch to publicly disclose his tax payments, revealing that he contributed £12.9million to HM Revenue & Customs during the 2024-25 financial year.
Palace officials announced on Thursday that since ascending to the throne in 2022, the sovereign has paid more than £30million in total taxation.
The unprecedented disclosure marks a significant moment in royal financial transparency, building on the arrangement first established when the late Queen agreed to pay income tax in 1993.
His Majesty's tax liability is calculated on his privy purse income, derived primarily from Duchy of Lancaster profits totalling £25.2million.