The Estate - which oversees a property portfolio belonging to the King - filed a claim against Twitter in the High Court in London last week, according to Reuters news agency.
The alleged arrears relate to office space near Piccadilly Circus in central London, the BBC has been told.
It comes after Elon Musk, the world's second richest man, paid $44bn (£36bn) to take control of Twitter in October last year before slashing more than half of the firm's global workforce of around 7,000.
The Crown Estate took legal action after previously contacting Twitter about rental arrears over office space at Air Street.
Read more: https://www.bbc.com/news/uk-64381582
The King of England is suing Musk for back/current rent.
The richest man in the US vs the richest man in England. The filthy rich exchanging wealth.