Accidental HMOs in London: How the Renters' Rights Act Could Catch Landlords Off Guard

A New Era of Tenant Turnover Has Quietly Begun

As of 1 May 2026, the Renters' Rights Act has officially converted all assured shorthold tenancies in England into periodic tenancies. In plain English, that means every tenant now has the right to leave with two months' notice, at any time, without waiting for a fixed term to expire.

For many London landlords, this feels like a manageable shift. But if you rent a property to a group of sharers, this change carries a hidden risk that could cost you tens of thousands of pounds. When one tenant in a shared flat leaves and is replaced by someone unrelated to the remaining occupants, the composition of your household changes. And that change can quietly tip your perfectly legal property into the territory of an unlicensed House in Multiple Occupation, better known as an HMO.

Councils across England are already cracking down. Peterborough and Tower Hamlets have issued five-figure penalties to landlords who were operating HMOs without realising it. As LandlordZone recently warned, many landlords simply don't know they have an HMO on their hands until enforcement action lands on their doorstep.

What Exactly Makes a Property an HMO?

The legal definition is more straightforward than most landlords expect, and that's precisely what makes it so easy to fall foul of.

A property is classed as an HMO if:

• It is occupied by three or more tenants forming two or more separate households
• The tenants share one or more basic amenities such as a kitchen, bathroom, or toilet
• At least one tenant pays rent or contributes to living costs

A "household" in this context usually means a family unit or a cohabiting couple. Three friends who aren't related to each other and who share a kitchen? That's three separate households. Your property is now an HMO.

Why the Renters' Rights Act Makes This Worse

Under the old fixed-term tenancy model, a group of tenants typically signed a joint AST together and stayed put until the term ended. The household composition remained stable, and landlords had reasonable visibility over who was living in their property.

Now, with rolling periodic tenancies, any individual tenant can hand in notice and walk away. The remaining tenants may want to stay and find a replacement. If that replacement is unrelated to everyone else in the flat, the number of separate households can increase overnight.

What was a straightforward two-household arrangement on Monday can become a three-household HMO by Friday. And unless you've secured the right licence, you're in breach of the law.

The Real Cost of Getting This Wrong

The penalties for running an unlicensed HMO in London are not trivial.

• Civil penalties of up to £30,000 per offence (and some councils are pushing for the maximum)
• Criminal prosecution with unlimited fines
• Rent Repayment Orders (RROs) where tenants can reclaim up to 12 months of rent
• Loss of the ability to serve a Section 21 notice (though this is now largely academic under the new Act)

Perhaps worst of all, tenants themselves can apply for an RRO. With growing awareness of tenant rights, this is becoming increasingly common. A landlord who never intended to operate an HMO can find themselves repaying thousands in rent to tenants who knew exactly what they were doing.

What London Landlords Need to Do Right Now

If you let a property to sharers in London, here is your checklist.

1. Audit Your Current Tenant Mix

Do you know how many separate households are living in your property right now? If you have three or more unrelated individuals sharing facilities, you likely have an HMO.

2. Check Your Borough's Licensing Requirements

Mandatory HMO licensing applies across England for properties with five or more occupants forming two or more households. But many London boroughs, including Newham, Waltham Forest, Barking and Dagenham, and others, operate additional licensing schemes that capture smaller HMOs too. You need to check your specific borough's requirements, because the rules vary significantly.

3. Build Tenant Replacement Controls into Your Process

With periodic tenancies making turnover more fluid, you need a system for vetting and approving replacement tenants. Every substitution is a moment where your property's legal classification could change.

4. Understand the Compliance Burden

HMO licensing isn't just a form and a fee. It comes with obligations around fire safety, room sizes, amenity ratios, gas and electrical certificates, and ongoing management standards. For many landlords, the cost and complexity of full HMO compliance simply doesn't justify the rental income from a shared property.

The Bigger Question: Is Shared Letting Still Worth the Risk?

This is the conversation that more and more London landlords are having with the team at Airhosts.

The traditional shared letting model was already operationally demanding. You were managing multiple tenant relationships, navigating deposit disputes, handling maintenance requests from several people with competing priorities, and trying to keep everyone happy under one roof.

Now, layer on the accidental HMO risk, the licensing fees, the compliance requirements, the threat of five-figure penalties, and a regulatory environment that is only getting stricter. For a growing number of property owners, the maths simply doesn't add up.

This is where short-term letting offers a genuinely compelling alternative.

Why Short-Term Lets Sidestep the HMO Trap Entirely

A professionally managed short-term let operates on a completely different model. Your property is let as a single unit to one booking at a time. There are no multiple households, no shared amenity calculations, and no risk of accidentally creating an unlicensed HMO through tenant turnover.

Beyond the regulatory simplicity, the financial upside is significant. Well-managed short-term lets in London consistently outperform traditional AST rentals, often generating 30% to 60% higher gross income. You maintain full flexibility over your property, avoid the new periodic tenancy framework entirely, and benefit from professional pricing strategies that respond to London's dynamic demand patterns.

Let Airhosts Handle the Complexity for You

At Airhosts, we specialise in turning London properties into high-performing, fully compliant short-term lets. We handle everything from listing optimisation and dynamic pricing to guest management, cleaning, and regulatory compliance. Our landlords enjoy hands-off, high-yield income without navigating the increasingly treacherous landscape of long-term letting regulations.

Whether you currently let to sharers and want to explore a safer, more profitable model, or you have a property sitting underutilised, we can show you exactly what your property could earn.

Your Property Deserves a Strategy That Works in 2026

The Renters' Rights Act has changed the game for shared properties, and the accidental HMO risk is real, growing, and expensive. If you are a London landlord who wants higher returns, fewer regulatory headaches, and a genuinely hands-off experience, it is time to talk to Airhosts. Get in touch today for a free property assessment and discover what your property could be earning as a professionally managed short-term let.