The Royal Trustees
The Royal Trustees are the body which determines the annual grant of public money to the monarch, as provided for by the Sovereign Grant Act 2011. 

The Royal Trustees were established by section 10 of the Civil List Act 1952. The members of the body are the Prime Minister, the Chancellor of the Exchequer and the Keeper of the Privy Purse. The Keeper of the Privy Purse is a royal household official*.