It comes from the treasury and it's funded by taxpayers, according to the BBC.
The basic agreement is that the Queen gets the grant in exchange for surrendering all profits from the Crown Estate — the family's massive portfolio of properties — to the government. Every year, the Queen is given an amount of money equivalent to 25% of the Crown Estate's profits.
The Grant totaled $107.1 million (£82.2 million) in 2019, The Wall Street Journal reported.
The Sovereign Grant pays for the family's travel, palace upkeep and utilities, and royal employee payroll, according to official royal family financial reports. But The Telegraph notes that the grant doesn't cover costs of security and royal ceremonies — that money comes from a few other places.