A British parliamentary committee is calling for greater oversight over the finances of the Duchy of Cornwall, an estate owned by the Prince of Wales that some suggest has an unfair advantage in the market.

The land entitlement, set up by King Edward III in 1337 in an effort to secure an income for his heirs, is being called into question after report by the U.K.’s Public Accounts Committee.

As Duke of Cornwall, Prince Charles is entitled to income derived from the vast estate – some 54,000 hectares that is worth more than $1 billion. Last year alone, it provided the heir to the throne with a salary of $30 million.

Prince Charles uses the money to fund royal duties, charity work and his family expenses. Although it is not a requirement, he has voluntarily paid personal income tax since 1993. Last year he paid $4 million in personal taxes.

Still, the duchy’s multi-million dollar land deals are exempt from corporation and capital gains tax.

“If you’re letting property to a Holiday Inn in Reading or to Waitrose to run a big depot on an industrial estate … are the terms of that enabling other competitors in the market to compete on an equal and level playing field,” said Public Accounts Committee chair and British MP Margaret Hodge.

For their part, representatives for the Duchy of Cornwall say it is not a problem.

“We do not believe we have a competitive advantage,” said the spokesperson for the Duchy of Cornwall, in a statement. “The Duke of Cornwall’s income is taxed at income tax rates. The Duchy is not subject to corporation tax and the Duchy is not a corporation.”

But observers say the benefits are undeniable.

“Undoubtedly, in the field of capital gains, the duchy does have an advantage because it doesn’t need to pay capital gains tax when it sells and makes a profit on property held for investments,” said Patrick Stevens, past president of the U.K.’s Chartered Institute of Taxation.

With a report by 鶹ý’ Ben O’Hara-Byrne