Boris Johnson is to officially take up residence in Downing Street, and Number 10 confirmed his girlfriend, Carrie Symonds, will be living with him.
A Downing Street spokeswoman said: “The PM is officially moving in today and, yes, his partner will be living there.”
Despite speculation that Mr Johnson may have needed new furniture to be paid for by the state, the spokeswoman said: “There’s no cost to the taxpayer.”
The spokeswoman said: “In relation to her living at Number 10, there won’t be any additional cost to the taxpayer.”
They will be the first unmarried couple to officially live in Number 10.
The couple had been living together at Ms Symonds’s flat in Camberwell, south London, until a well-publicised row recorded by neighbours last month.
Both Mrs May and former chancellor Philip Hammond left their flats in Downing Street as the handover to Mr Johnson’s new administration took place.