Today, three per cent (981,000) of homeowners are boosting their income by renting out spare rooms and a further three per cent have said that they are currently considering taking in a lodger.
Those people who have taken in a lodger are now earning an average of £393 a month or £4,716 a year in rental income - just over the Government's Rent a Room scheme's tax free threshold of £4,250.
Abbey Mortgages found that 16 million UK homeowners have at least one spare room and if all of these rooms were to be let, homeowners would collectively reap as much as £6.29 billion in lodger loot.
Homeowners in London were the most likely to take in a lodger at 6 per cent, compared to just 1 per cent in Scotland and Northern Ireland.
Nici Audhlam-Gardiner, Director of Alliance & Leicester Mortgages, commented: "If you have a spare room that's gathering dust, its worth considering a lodger and earning £4,716 a year. Not only will you have some extra money each month but most of it could be tax-free too. Those homeowners who still have spare rooms to rent are collectively missing out on over £6billion a year.
"For homeowners who are not so keen to take in a lodger, A&L offers some market leading rates including a best buy tracker at 2.95 per cent, to reduce the monthly mortgage bill."
