“The duchies – worth £1.8 billion – are the personal property of King Charles and Prince William, but they are exempt from corporation tax and capital gains tax.”
I’m not misleading, no. Your statement above is misleading in three separate respects, though!
The Duchies are legally independent from Charles and William. So William and Charles are not liable to pay corporation tax (no individual pays corporation tax, by the way). And neither of them are entitles to the proceeds or profit on the sale of capital assets held by the Duchy – they only receives the annual income which they generate. So they would have no liability to pay capital gains tax, given that.
It’s also not correct that the Duchies are their personal property. In some respects, they are more akin to trusts - the assets are managed by a board of trustees for defined purposes. As noted above, neither Charles nor William can sell an asset and take the proceeds of sale.
They way they operate for tax purposes is similar to the way a partnership works int the UK. If you take a large firm like KPMG for example, its turnover is in the hundreds of millions, and its profit is in the millions. It doesn’t pay corporation tax, however. Its profits are distributed between its many partners, and each of them personally pays income tax on those. That’s what William and Charles do with the profits of the Duchies.
Also, on charging rents to tenants like the NHS or the army, the Duchies are actually legally required by Parliament to do this, and Treasury policies it. From HMT’s Memorandum about them approving the Duchy’s transactions:
When assessing proposed large property transactions under s11 of the Act,
the Treasury seeks evidence that the terms are commercial. Helpful indicators include:
• for sales, competition among potential purchasers and at settlement prices in
line with estate agents’ guide prices;
• for investment and development projects, actual or expected returns at market
level