Scope: England. Wales uses occupation contracts with their own sub-occupation rules. Verified 10 August 2026.
The risk here is asymmetric, and not in the direction landlords expect. The tenant breaches the agreement; the licensing offence is yours.
Subletting and lodgers are not the same thing
- Subletting — the tenant grants another person exclusive possession of the whole or part of the property. The subtenant has a tenancy from your tenant.
- Taking a lodger — someone shares the accommodation with the tenant, who remains resident. The lodger is a licensee, not a tenant, and has far weaker rights.
Most agreements treat them differently, and the distinction matters because a resident tenant with a lodger is a different licensing and possession picture from a tenant who has moved out and let the whole place.
What the tenancy usually says
Nearly every agreement prohibits subletting without written consent, and many prohibit lodgers too. Where consent is required, a term that it will not be unreasonably withheld may be implied or express — but a flat prohibition is generally enforceable.
Read the actual clause. A blanket "no subletting" and a "not without consent, such consent not to be unreasonably withheld" produce different answers when a tenant asks.
Where an unauthorised sublet leaves you
No direct relationship with the occupier
An unlawful subtenant has no tenancy from you. Their rights come from your tenant, and generally cannot outlast your tenant’s own tenancy. Ending the head tenancy usually ends theirs — though they are still occupiers who must be removed lawfully, never summarily.
The licensing exposure, which is the real one
This is the point of the article. If your tenant sublets rooms to unrelated occupiers, the property may become an HMO — three or more people from two or more households sharing an amenity.
And if it becomes a licensable HMO, the offence of controlling or managing an unlicensed HMO under section 72 falls on the person managing or having control. That includes you. Consequences:
- an unlimited fine or a civil penalty up to £30,000;
- a rent repayment order of up to twelve months’ rent — claimable by the occupiers or the council;
- possession barred while unlicensed.
"I did not know my tenant had sublet" is a difficult position, not an automatic defence. Reasonable excuse is fact-specific, and a landlord who never inspected has less of one.
The other exposures
- Insurance — most policies are voided or restricted by unauthorised subletting.
- Mortgage — buy-to-let terms commonly prohibit it.
- Council tax — an HMO in scope of the 2023 regulations makes the landlord liable. See HMO council tax.
- Fire safety — a property let as a single household and occupied as a shared house has the wrong alarm system for its actual use.
What to do if you find one
- Establish the facts — how many occupiers, from how many households, since when, what is shared. That determines whether you have an HMO.
- Deal with licensing first, not last. If it is licensable, apply. A property is not treated as unlicensed while a valid application is being determined, and that protection is worth more than winning the argument with your tenant.
- Write to the tenant setting out the breach and requiring it to stop by a date.
- Tell your insurer.
- Consider Ground 12 — breach of a tenancy term, discretionary, 2 weeks' notice. See the grounds table.
- Never approach the occupiers to remove them yourself.
Consenting deliberately
Sometimes the right answer is yes — a tenant who needs a lodger to afford the rent is a tenant who keeps paying. If you consent:
- do it in writing, naming the person and the arrangement;
- work out whether it makes the property an HMO, and licence it if so;
- tell your insurer and check your mortgage terms;
- review the fire safety provision for the actual occupancy.
Wales
Occupation contracts have their own rules on lodgers and sub-occupation contracts, and Rent Smart Wales licensing sits on top regardless. See occupation contracts and the divergence map.
Does the clause say what you think it says? Check the agreement — findings cited to the Act and section.
Information tool, not legal advice.