What is a house in multiple occupation?
A house in multiple occupation is a property occupied by more than one household where occupants share basic amenities such as a kitchen, bathroom or toilet. In planning and housing law, this typically refers to unrelated people living together who do not form a single family unit.
HMOs can range from small shared houses occupied by three or four individuals to large HMOs accommodating seven or more people. The Housing Act 2004 governs HMO licensing, while the Town and Country Planning framework determines whether a change of use requires planning permission.
The fact that a property is classed as a house in multiple occupation for licensing purposes does not automatically determine whether planning permission is required.
Planning permission and use classes
Planning permission for HMOs is governed by the Town and Country Planning (Use Classes) Order. Residential properties fall into different use classes depending on how they are occupied.
A standard dwelling house occupied by a single family or a single person usually falls within Class C3. Small HMOs, occupied by up to six unrelated people who share amenities, fall within Class C4. Large HMOs housing seven or more people are treated as sui generis, meaning they fall outside standard use classes.
A change from a dwelling house (C3) to a small HMO (C4) is often permitted development, meaning it does not usually require planning permission. However, this position can change depending on local planning policy.
Article 4 directions and HMOs
An Article 4 direction allows a council to remove permitted development rights in specific areas. Where Article 4 applies, a change from a dwelling house to a small HMO will require planning permission even if the number of occupants is below seven.
Article 4 directions are commonly introduced in areas with high concentrations of HMOs, where councils believe further conversions would place increased pressure on local services, public transport, or housing supply. Cities with large student populations or dense rental markets are particularly affected.
Landlords should always check whether Article 4 applies before converting a property. Councils publish Article 4 maps and guidance, often through the planning portal.
Do you need planning permission for an HMO?
HMO planning permission may be required in several situations:
- Where a property is converted into a large HMO housing seven or more people.
- Where the local council has introduced an Article 4 direction removing permitted development rights.
- Where a property moves between use classes in a way not covered by permitted development.
- Where planning conditions restrict the number of occupants or type of use.
In these cases, landlords will need to submit a planning application and obtain planning approval before operating the property as an HMO.
Failing to secure permission where required can lead to enforcement notices, limits on occupation and difficulties obtaining or renewing an HMO licence.
Do all HMOs need planning permission?
Not all HMOs need planning permission. In areas without Article 4 restrictions, a small HMO with up to six occupants may operate under permitted development. However, large HMOs always require planning permission due to their sui generis status.
The difficulty arises where landlords obtain an HMO licence but later discover that planning permission was also required. Licensing and planning are assessed separately by different departments within the council, and approval under one regime does not override the other.
HMO licensing and planning - how they interact
HMO licensing focuses on housing standards, safety and management arrangements. Planning permission focuses on land use, density, and local impact.
A landlord may hold a valid HMO licence but still be in breach of planning control. Conversely, a property may have planning permission but fail to meet HMO licensing requirements.
Operating without the correct permission can expose landlords to enforcement action, rent repayment orders and restrictions on serving possession notices. Councils increasingly cross-check licensing and planning records, particularly for new HMOs.
Can you turn any house into an HMO?
Not every house is suitable for conversion into an HMO. Planning policy often considers factors such as:
- High concentrations of existing HMOs.
- Impact on neighbouring residents.
- Loss of single-family housing.
- Availability of affordable accommodation.
- Waste management and parking provision.
Even where permitted development applies, councils may refuse planning applications for large HMOs if policy criteria are not met.
Lawful development certificates
Where planning status is unclear, landlords may apply for a lawful development certificate. This confirms that the existing use of the property is lawful for planning purposes.
A lawful development certificate can be particularly helpful where an HMO has been operating for a long period without enforcement action, or where permitted development rights applied at the time of conversion. This can provide certainty for lenders, buyers and future licensing applications.
Neighbours and objections
Landlords often ask whether neighbours can stop an HMO. Neighbours do not have a veto, but they can object during the planning application process. Councils will consider objections relating to planning matters, such as noise, parking, or overdevelopment.
Objections based purely on dislike of HMOs or tenants generally carry less weight, but cumulative impact and high concentrations may influence decisions.
Risks of getting HMO planning wrong
Failing to comply with planning requirements can lead to:
- Enforcement notices requiring cessation of HMO use.
- Restrictions on occupation numbers.
- Difficulty renewing an HMO licence.
- Rent repayment orders affecting rent already received.
- Problems refinancing or selling the property.
Planning breaches can also undermine possession proceedings if the property is unlawfully used.
New HMOs and changing policy
Local authorities continue to tighten planning policy around new HMOs, particularly in cities and boroughs experiencing increased pressure on housing stock. Government guidance allows councils to manage density through Article 4 directions and planning criteria, and this trend is unlikely to reverse.
Landlords considering new HMOs should assess planning risk carefully before purchase or conversion.
How AST Assistance supports landlords
AST Assistance works exclusively with landlords and provides focused, practical advice on the interaction between HMO licensing, planning permission and enforcement risk. We support landlords at every stage - from assessing whether planning consent is required, to reviewing existing HMO arrangements and responding to challenges raised by local authorities.
Our advice covers small and large HMOs, Article 4 Directions, lawful development certificates and enforcement action. Where planning issues affect your ability to let, recover rent or pursue possession, we provide clear, legally grounded guidance so you can proceed with confidence and minimise disruption to your portfolio.
If you are planning to convert a property into an HMO, expanding an existing arrangement, or unsure whether your current use is lawful, early advice can prevent costly mistakes and long-term complications.
AST Assistance also offers end-to-end support with HMO sourcing and management through our dedicated property investment service, helping landlords identify suitable opportunities, assess compliance risks and manage properties effectively.
For landlord-focused advice on HMO planning permission, licensing and enforcement risk, contact AST Assistance on 01706 619954 or fill out an online contact form and one of our team will get back to you.
