Yes. 85% of it usually. 75% of it for the next ten years.
No that money belongs to the Proles, it's not the Monarch's money. Her great x4 grandfather agreed that the Exchequer would keep all the positive revenues from the Crown Estate as part of the deal he did with the Government of the day to cover the Monarchs debts and the costs of running the Government.
Putting that to one side let me help you out on this one.
The Crown Estate model of funding the Monarchy through the 15% rule introduced in 2012 ( subject to review and change every five years) is flawed. It was only done to avoid the "embarrassment" ( to the Monarchy ) of the old civil list review.
Why not make the Crown Estate responsible for the repairs to these Palaces?
The Monarch would then receive less money as her expenses would be less.
The Crown Estate would be set aggressive profit targets by the Government, so that in this case of the additional cost of the repairs to the Palace , it would not be sufficient for them to simply post lower profits, they would have to increase revenues,sell off assets ( they own billions),cut costs , maybe even borrow in the short term, improve investment returns or even innovate. In short do what any other business would do.
Liz's expenses would be subject to audit of course and if necessary reduced.
This way everyone is happy.
Liz gets her money and Buck Palace is repaired without any reduction in the profits from the Crown Estate because it is now run as an efficient business and can make up the additional costs of Buck Palace through business efficiencies.
Taxpayer doesn't lose out.
Job's a good 'un.