More than 18,000 people availed of a lucrative tax relief for renting out a room in their home, nearly double the number from six years earlier, the most recently published figures show. The relief, which allows homeowners with a spare room to earn €14,000 rental income tax-free, was introduced in 2001 in a bid to ease housing pressures. It is soon to be expanded to include rooms let out in back-garden modular homes.The numbers claiming the relief have been rising steadily over the last decade, with 18,180 homeowners claiming the tax exemption in 2024, the most recent year for which data is available. This is nearly double the 9,240 who availed of the scheme in 2018, and a further increase on the 6,460 who benefited in 2016.The 2024 relief amounted to an estimated €47.3 million cost to the exchequer, up from €42.5 million the year before, when there were 16,580 claimants, according to figures from the Revenue Commissioners.The scheme provides that lodgers are not tenants but licensees, so they do not acquire protections under the Residential Tenancies Act. This tax-relief scheme is set to be expanded to include people lodging in back-garden cabins under proposals set to be introduced by Minister for Housing James Browne.[ Back-garden living incentives could expose older homeowners to abuse, charities warnOpens in new window ]The renters’ support charity Threshold has warned that licensees falling outside the scope of the Residential Tenancies Act are not afforded “essential rights” such as security of tenure, protections from high rent increases and access to a landlord-tenant resolution process overseen by the Residential Tenancies Board.Setting rental arrangements beyond the Act’s scope will lead to “legal uncertainty” and increase the risk of exploitation, particularly among vulnerable groups such as migrants, lower-income households and older people, the organisation said. It is regularly contacted by people classed as licensees in their accommodation and said many of these lodgers become aware of their legal status only when a crisis occurs, such as an eviction, the withholding of a deposit or a sudden deterioration in their living conditions.The rent-a-room relief figures were provided to Social Democrats housing spokesman Rory Hearne in response to a parliamentary question.[ Is a room rented under rent-a-room scheme restricted by RPZ rules?Opens in new window ]Hearne said the significant increase in claimants will have led to significantly more licensees living in “precarious housing”, and this is likely to further increase when modular homeowners are included in the scheme. “These renters are outside the Residential Tenancies Act. As a result they all are at risk of sudden eviction and have no access to a dispute-mediation mechanism,” he said. With limited rights when faced with eviction or disputes, he said, these people often exist in a “parallel rental sector” into which society has little insight.“The Government is looking to further expand this group with their beds-in-sheds idea, which will lead to some very vulnerable people being exploited,” he added.Minister of State for Planning John Cummins last week said he did not recall any arguments in the Dáil or the housing committee by anyone seeking to get rid of the rent-a-room relief. Answering a question from Hearne at the housing committee, Cummins said: “If it’s good enough within the four walls of the house, why would we not apply it within the curtilage of the dwelling?”Cummins said characterisations applied by some to back-garden dwellings do a disservice to the modular building industry, which is providing “high-quality homes”.