Over the past five years, UK room rents have risen by 28%, with the average now sitting at £747 per month according to SpareRoom’s latest rental index. That figure matters because it tells you something most people miss: renting out a spare room in your own home is no longer a small side hustle. It’s a serious income stream that, in many parts of the country, can rival the returns from a traditional buy-to-let property — without needing a second mortgage.
I’ve been watching the UK rental market for years, and one pattern keeps coming up. People assume buy-to-let is the only serious property investment. But the numbers tell a different story. The supply of lodger rooms has actually started to decline — ads fell 2.5% year on year in January 2026 — which means demand is outstripping supply. That’s a landlord’s market, whether you own the whole building or just have a spare bedroom. Here’s what you actually need to know.
How the Rent a Room Scheme actually works
The most important thing to understand is that the Rent a Room Scheme isn’t a tax loophole. It’s a specific government allowance that lets you earn up to £7,500 a year tax-free from letting furnished accommodation in your own home. If you’re married or in a civil partnership and you let jointly, the allowance is halved to £3,750 each. Go over that threshold and the whole amount becomes taxable — not just the excess. That’s the trap most people miss.
What I’d do if I were starting today: check whether the Rent a Room Scheme or the normal rental income rules work better for you. If your costs are high — say you live in an expensive area and your mortgage interest is significant — deducting actual expenses might save you more than the flat £7,500 allowance. You have to choose one or the other. You cannot mix them.
Why the timing has never been better for lodgers
The rental market is shifting in ways that directly benefit homeowners with a spare room. Over half of UK renters are now ‘flathugging’ — staying put because they cannot afford to move. That means fewer properties turning over, less choice for tenants, and more people willing to pay a premium for a room in a well-maintained home. At the same time, the supply of lodger rooms is shrinking. After four consecutive years of growth, lodger ads dropped 2.5% in early 2026. Fewer rooms available, more people looking — that’s the basic recipe for rising rents.
There’s also a demographic shift worth noting. Flatsharers are getting older. Spiralling living costs have pushed home ownership and solo renting further out of reach, so you’re increasingly seeing tenants in their 30s and 40s looking for shared accommodation. These are typically more stable, more reliable lodgers than the student or young professional you might have imagined. If you’re worried about having a stranger in your home, the profile of the average lodger today might put your mind at ease.
Where most homeowners get this wrong
I’ve seen the same mistakes come up again and again. Here are the ones that cost people the most money.
Assuming buy-to-let is always more profitable
People look at the gross rent on a whole property and assume it beats a single room. But they forget to subtract the costs. A buy-to-let means stamp duty (an extra 3% if you already own a home), mortgage arrangement fees, landlord insurance, gas safety certificates, EPCs, letting agent fees, and void periods between tenants. A lodger in your own home means none of those things. The average UK room rent of £747 gives you £8,964 a year. The first £7,500 is tax-free. On a buy-to-let, every pound of that rent is taxable after your allowable expenses — and you cannot claim mortgage interest as a full expense anymore. The net return is often closer than you think.
Forgetting the Rent a Room threshold is a cliff edge
If your lodger pays you £7,500 a year, you pay no tax. If they pay £7,501, you pay tax on the full £7,501 — not just the extra £1. That’s a brutal marginal rate. The fix is simple: keep the rent at or below £625 per month (£7,500 ÷ 12). If market rates in your area are higher, consider whether opting out of the Rent a Room Scheme and using normal rental income rules with actual expense deductions would leave you better off. Run the numbers before you set the rent.
Ignoring the impact on your home insurance
Standard home insurance policies often exclude or limit cover for paying guests. If your lodger’s belongings are stolen or they cause damage, you might find your claim rejected. A quick call to your insurer to add lodger cover costs very little and saves a lot of hassle. While you’re at it, a smart water leak detector in the en suite or near the plumbing can catch small problems before they become big disputes.
| Region | Average room rent | 5-year change |
|---|---|---|
| UK average | £747 | +28% |
| London | £985 | +37% |
| Wales | £586 | +40% |
| Edinburgh | £823 | — |
Not checking whether your mortgage allows it
Most residential mortgages allow you to take in a lodger without permission, but some don’t. A few lenders specifically prohibit it. Check your mortgage terms before you advertise the room. If you need to switch to a consent-to-let arrangement, factor in any fees. It’s a five-minute phone call that could save you a breach of contract.
How to set up a lodger arrangement the right way
Writing about topics like this takes real time and research. If you buy something through an Amazon link on this page, I may earn a small commission — at no extra cost to you. It’s one of the things that makes it possible to keep BritWealth free to read. I only link to products that are genuinely relevant to the article.
Getting this right is about more than just finding someone to fill the room. Here’s the process I’d follow.
Set the right rent and choose the right tax route
Start by checking what similar rooms in your area are actually achieving. SpareRoom’s rental index is a good benchmark. If the market rate in your area is above £625 per month, you have a decision to make. You can cap the rent at £625 to stay within the tax-free allowance, or you can charge market rate and opt out of the Rent a Room Scheme, declaring the income under normal property rules and deducting your actual expenses. The right choice depends on your mortgage interest, utility bills, and how much of the home the lodger uses. If you’re unsure, a financial advisor can run the comparison for you in about 15 minutes.
Write a simple lodger agreement
Unlike a buy-to-let tenancy, a lodger has limited rights. They are a licensee, not a tenant, which means you can ask them to leave with reasonable notice — typically the length of the rental period. But you still need a written agreement covering rent, bills, notice period, house rules, and use of shared spaces. A tenant landlord lawyer can draft one that protects both of you. Do not rely on a handshake. I’ve seen too many disputes that could have been avoided with three pages of paper.
Prepare the room and the house
The room needs to be furnished — that’s a condition of the Rent a Room Scheme. It doesn’t have to be luxury, but it does need a bed, storage, a desk or table, and a chair. A lockable bedroom door handle gives your lodger privacy and you peace of mind. Check your smoke alarms and carbon monoxide detectors are working. If you don’t have one, a carbon monoxide alarm is cheap and non-negotiable when someone else is sleeping under your roof.
Screen lodgers properly
You are going to share your kitchen, bathroom, and living space with this person. Take your time finding the right fit. Use a platform like SpareRoom that allows you to message and meet potential lodgers before committing. Ask for references from a previous landlord or employer. Trust your instincts — if something feels off during the viewing, it will feel worse at 11pm on a Tuesday. What I’d do: meet them in person at least twice before agreeing anything. The extra hour of your time now saves months of awkward living later.
Frequently asked questions
Can I use the Rent a Room Scheme if I have a mortgage? ▾
What happens if my lodger refuses to leave? ▾
Does the Rent a Room Scheme cover bills included? ▾
Can I take in more than one lodger? ▾
Do I need to tell the council or HMRC? ▾
The case for renting out a spare room has never been stronger. You avoid the upfront costs of a second property, benefit from a generous tax allowance, and tap into a market where demand is rising and supply is falling. My advice: check your mortgage terms, set the rent at or just below £625 per month, and write a proper agreement before anyone moves in. If this was useful, you might also want to read Is co-living the future of UK property?
Sources and Further Reading
Creative financing for UK property purchases — Practical alternatives if you’re thinking about expanding beyond a single lodger room.
SpareRoom Rental Index and Market Reports. SpareRoom, 2025–2026.
Buy-to-let vs short-term lets: which offers better returns?. PropertyData, 2025.
