Current Revenue guidance says a self-contained unit can qualify only if it is within the home, such as a basement flat or converted garage. It also says that if the unit is not attached to the property, it cannot qualify for the relief.
That means detached units do not currently qualify under the published Revenue guidance. The April 2026 government announcement says the Minister for Finance will consider tax arrangements for auxiliary dwellings and Rent-a-Room interaction through the normal Budget and Finance Bill process.
Until that text is published and in force, homeowners should not budget on detached garden-unit income being relieved in the same way as a room inside the main home.
Short-term leisure letting is also outside Rent-a-Room relief under current Revenue conditions. This site does not promote short-term guest accommodation as a tax-relief strategy.
Why this distinction matters
Many homeowners search for modular units because the rent figure looks like it could repay the build cost. The tax treatment is one of the biggest assumptions in that calculation. If income is not relieved, the net return can be much lower than the headline monthly rent.
Revenue's current distinction is also practical: a room or qualifying self-contained unit within the home is not the same thing as a detached garden dwelling. A detached unit may have separate access, services, insurance, planning and valuation questions.
Safer way to model rental use
Until the law changes, model detached-unit rental income as taxable unless your own tax adviser says otherwise. Include insurance, repairs, maintenance, vacancy, utilities, compliance, financing, and any property-related charges. If future Budget or Finance Bill wording creates a specific relief, update the calculation then.
For family use, the question may be less about income and more about avoided rent, care, privacy, or keeping family close. Those benefits can be real, but they should not be mixed with a tax-free rental claim.
What to ask before relying on income
Ask a tax adviser whether the proposed use fits current Revenue rules, and ask a planning adviser whether the intended occupation changes the planning position. Then ask suppliers whether the specification is suitable for year-round residential use, including heating, ventilation, fire safety, services, warranties and aftercare.