Harrow and Hillingdon Tighten HMO Planning Rules
London boroughs Harrow and Hillingdon have introduced Article 4 directions, requiring planning permission to convert family homes into small HMOs.
Harrow and Hillingdon have introduced Article 4 directions requiring planning permission for converting family homes into small HMOs for three to six unrelated occupiers, tightening control over shared housing development. Nationally, HMO planning applications rose 87% between 2021 and 2025, from 1,848 to 3,454, while refusals more than doubled from 590 to 1,203.
Harrow has introduced a borough-wide Article 4 direction. Hillingdon has extended its HMO controls across the borough. They are among the latest councils to implement such measures.
Planning permission now required for many conversions
Article 4 directions mean that small HMO conversions, which would otherwise be allowed without planning permission, must now undergo full council assessment. This allows councils to evaluate proposals against policies on housing mix, neighbourhood character, and HMO concentrations. Harrow’s evidence base recognises the role HMOs play in meeting housing need but also highlights concerns about over-concentration and the impact on neighbourhoods.
Licensing requirements apply to larger HMOs
Separate licensing rules also govern the sector. Under the Housing Act 2004, landlords letting to five or more people from two or more households who share facilities must hold a valid HMO licence. Some councils have extended licensing requirements to smaller HMOs. Operating without a licence is a criminal offence. It can result in civil fines of up to £30,000 per offence, rent repayment orders for up to 12 months' rent, prosecution, and inclusion on the database of rogue landlords and agents.
Affordable housing demand drives HMO use in London
In London, where rents remain the highest in the country, HMOs are often the only affordable option for students, young professionals, and lower-paid workers. The tightening of planning rules reflects the challenge facing councils balancing housing need with community impact.
Approval rates for HMO applications remained steady at around 68 per cent between 2021 and 2023, but dropped to 63 per cent in early 2026. The upcoming Renters' Rights Act, which will abolish fixed-term tenancies and Section 21 ‘no-fault’ evictions once enacted, could make HMOs more attractive to some landlords compared to single lets.
Housing bodies warn that reducing legitimate HMO supply without addressing demand could drive people into less visible arrangements. Property expert Paul Endacott said: "The uncomfortable truth is that somewhere else is often less visible and less safe." The National Residential Landlords Association has previously argued that Article 4 restrictions can disproportionately affect students and young people. Shared housing in London is under threat due to rising planning restrictions.
