“[Royal wills] are hidden, so we have no idea actually what’s in them and what that’s worth, and that’s never ever made public,” Laura Clancy, a lecturer in media at Lancaster University and author of a book on royal finances, told CNN Business.
The line of succession makes Prince William, now the first in line to the British throne, a much wealthier man.
The future king inherits the private Duchy of Cornwall estate from his father. The duchy owns a sprawling portfolio of land and property covering almost 140,000 acres, most of it in southwest England.
Created in 1337 by King Edward III, the estate is worth around £1 billion ($1.2 billion), according to its accounts for the last financial year.
Revenue from the estate is “used to fund the public, private and charitable activities,” of the Duke of Cornwall, its website says. That title is now held by Prince William.
The estate includes vast swathes of central London property and the seabed around England, Wales and Northern Ireland. It has the status of a corporation and is managed by a chief executive and commissioners — or non-executive directors — appointed by the monarch on the recommendation of the prime minister.
In the last financial year, it generated a net profit of almost £313 million ($361 million). From that, the UK Treasury paid the Queen a Sovereign Grant of £86 million ($100 million). That’s equivalent to £1.29 ($1.50) per person in the United Kingdom.
Most of this money is spent on maintaining the Royal family’s properties and paying their staff.
The Sovereign Grant is usually equivalent to 15% of the estate’s profits. But, in 2017, the payment was bumped up to 25% for the next decade to help pay for renovations to Buckingham Palace.
King Charles also inherits the Duchy of Lancaster, a private estate dating back to 1265, which was valued at about £653 million ($764 million) according to its most recent accounts. Income from its investments cover official costs not met by the Sovereign Grant, and aids support other Royal family members.
The King can only spend the Sovereign Grant on royal duties. And neither he nor his heir are allowed to benefit from the sale of assets in their duchies. Any profit from disposals are reinvested back into the estate, according to an explainer published by the Institute for Government’s (IfG).
The UK Treasury must also approve all large property transactions, the IfG said.
Still, unlike the Sovereign Grant generated by the Crown Estate, both Duchies are private sources of wealth, meaning their owners are not required to give any details beyond reporting their income, the IFG said.
Last year, King Charles, then the Duke of Cornwall, paid himself £21 million ($25 million) from the Duchy of Cornwall estate.
That move came a year after the Royal family faced strong criticism for planning to use public money to repair Windsor Castle, which had suffered damage in a fire, Clancy said.
“Of course, voluntary income tax [is] not a fixed rate, and they don’t have to declare how much income they’re making on their tax. So actually it’s just like plucking a figure out of thin air,” said Clancy.
Buckingham Palace did not immediately respond to CNN Business when reached for comment.