Managing a tenancy

Subletting and Unauthorised Occupants: What Landlords Can Do

Managing a tenancy · 6 min read

You let the property to two named tenants — and then you notice there seem to be four people living there, or a stranger answers the door, or your flat appears on a short-let site booked out most weekends. Subletting and unauthorised occupation are among the more common headaches in letting, and they matter far more than "someone extra is living there". When people you didn't approve move in, a stack of compliance risks quietly transfers to you: unchecked occupiers, a property that's tipped into HMO territory, voided insurance, breached mortgage or lease terms. Here's how to tell a genuine breach from a non-issue, what's actually at stake, and how to deal with it without overstepping. This is general guidance, not legal advice — verify the position on GOV.UK and take advice before acting on a breach.

What actually counts

"Subletting" gets used loosely, so it helps to separate the situations:

Subletting — the tenant lets all or part of the property to someone else, creating their own arrangement with a third party.
Taking in a lodger — someone lives with the tenant and shares the space, usually paying them.
Unauthorised occupiers — extra people simply move in, named on nothing.
Short-term letting — the tenant lists the property (or a room) on a holiday-let platform for paying guests.

Not all of these are automatically a problem — a partner moving in may be perfectly reasonable, for instance — but each is governed by what your tenancy agreement permits and by law. A well-drawn agreement sets out clearly whether subletting, assignment, lodgers or parting with possession are allowed, and on what terms. The short-let scenario is almost always a clear breach, and often tangles up planning, licensing and leasehold rules on top.

Why it matters: the risks land on you

This is the part landlords underestimate. When occupation changes without your knowledge, the consequences attach to you as the owner:

Right to Rent. You're expected to have checked every adult occupier's right to rent — people who moved in unchecked are a gap in your compliance, not the tenant's.
HMO and over-occupation. Extra households can tip a property into being an HMO that now needs a licence and meets higher standards — operate it unlicensed and the penalties are severe.
Insurance. A landlord policy is priced on how the property is used; undisclosed occupants or short-letting can leave you without cover when you claim.
Mortgage and lease terms. A buy-to-let mortgage or a leasehold title often restricts subletting and short-lets — a breach there is a separate, serious problem.
Condition and nuisance. More occupiers, or a churn of short-stay guests, usually means more wear, more complaints, and more risk to the deposit position.

The trap works both ways: ignore it, and you silently inherit every one of those risks — you could be running an unlicensed HMO or carrying unchecked occupiers without realising. But overreact, and you create a different problem: you cannot simply change the locks, remove someone's belongings or force anyone out, even an occupier with no agreement, without following the proper legal process — doing so risks an unlawful-eviction claim. The right path is between the two: establish the facts, then act through the correct channel. Check the position on GOV.UK and take advice.

How to handle it

Deal with it methodically rather than in a panic:

Establish the facts. A routine inspection with proper notice tells you who's actually living there and how the property's being used — document it with dates.
Check your agreement and the law. Work out whether what's happening is genuinely prohibited, or something you'd reasonably permit if asked.
Talk to the tenant first. Many cases resolve here — a partner can be added properly (with a Right to Rent check and records updated), or the tenant agrees to end a short-let arrangement. Confirm whatever's agreed in writing.
Put compliance right. If an occupier is staying, do the checks you'd have done at the start and reassess whether licensing or your insurance now needs updating.
Escalate a real, continuing breach properly. A serious breach of the tenancy can be a basis for possession under Section 8, but that's a formal route — served and evidenced correctly, with legal advice, not a self-help eviction.

The short-let problem specifically

A tenant sub-letting the whole property on a holiday platform is in a category of its own: it's usually a plain breach of the tenancy, frequently breaches the head-lease and mortgage, can trigger planning and licensing requirements, and exposes you to insurance and safety risks you never signed up for. Act on it promptly once you have evidence — this is one where leaving it to drift rarely ends well, and where taking advice early pays off.

What landlords should do now

Use a clear agreement that spells out the position on subletting, lodgers, assignment and short-letting.
Inspect periodically so you actually know who's living there and how the property's used.
Address changes early and in writing — regularise what's reasonable, don't let unchecked occupation build up.
Keep your compliance aligned — Right to Rent, licensing and insurance all need to match reality.
Follow the proper process for a genuine breach, and take legal advice rather than acting unilaterally.

Subletting and unauthorised occupation are really a compliance problem wearing a people problem's clothes: the issue isn't just who's there, it's that the duties you're judged on — safety checks, licensing, insured use, immigration checks — quietly stop matching what's actually happening in the property. Catch it early with regular contact and inspections, deal with it in writing, and use the formal route where you must. That keeps you both in control and on the right side of the process.

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General guidance for UK landlords, not legal advice. What a tenant may or may not do with the property, when occupation becomes a breach, HMO and licensing thresholds, and the process for dealing with a breach or removing an occupier are set by law and the tenancy agreement and can turn on the exact facts — always verify the current position at GOV.UK and take professional legal advice before acting.