People who take in lodgers are generally not taxed on rental income, Abbey has pointed out.
Homeowners currently feeling the squeeze of the credit crunch can relieve some of the pressure - by giving over an unused bedroom to a lodger.
According to analysis from Abbey, released today, a collective total of £63.4 billion extra could be earned if all of Britain's spare rooms were rented out, due to a over 18 million homeowners currently having space. Moreover, a separate poll conducted by the firm suggests that the idea could prove popular, with 1.6 million people reportedly considering taking in a tenant.
Abbey also found that around 388,000 Britons currently have a lodger.
The financial incentive for doing so is increased by the government's Rent a Room scheme, which allows householders to earn up to £4,250 from lodgers a year, tax free. The average annual working salary stands at around £25,000 before tax.
Phil Cliff, director of Abbey Mortgages, commented: "With income being squeezed in so many ways, those looking to raise some extra money may find that their spare room could provide the answer. Demand for rooms is likely to be fairly high too and with the government providing tax free incentives for landlords, now is certainly a good time for those considering taking in a lodger."
Abbey is the UK's largest mortgage lender.
