The Welsh singer has been staying in the exclusive Savoy hotel during filming, flying in from his home in America.
But at just under £700 a night, Sir Tom's three week stay has seen him notch up a huge bill."
However license payers will no doubt be pleased to learn that Sir Tom has made some savings, such as passing on the hotel's offer of a personal butler.
“Tom doesn’t have a butler — we’re at his beck and call so he doesn’t need one," a source told The Sun newspaper.
While Will.i.am also stays in hotels for the show, the newspaper reports that he has to pay out of his own pocket, while both Danny O’Donoghue and Jessie J both have homes in London.
A spokeswoman for the BBC said: “All coaches have their own agreements with the production company for the series.
“For Sir Tom Jones this includes his accommodation as he does not live in the UK.”
Meanwhile, Danny O'Donoghue spent £7,000 on flying finalist Andrea Begley out to the Isle Of Wight festival to watch him and The Script perform.
But BBC bosses refused to pay for the trip, instead only providing the amount it would've cost to go via the train and ferry.