According to rental specialists mondaytofriday.com, there are 15.5 million homes in the UK with at least one spare bedroom, and more than half that number with two or more empty rooms.

Under the Government’s Rent a Room scheme, homeowners – and renters whose contracts allow – can let out a room or rooms to lodgers and earn £4,250 a year tax free.

A higher rate tax payer would have to earn over £7000 to net the same amount in their pay packet.

Sam Hubbard, managing director of Encompass Financial Solutions, said:

“Using that tax free cash as a monthly overpayment on your mortgage could reduce your £100,000* mortgage term by over 10 years and save you over £20,000* in interest. These figures also ignore the added bonus that you will be mortgage free after 15 years”.

*Based on an interest-only mortgage with a 25 year term on an interest rate of 4%