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Planning Law

Change of Use Planning UK, Use Classes and HMOs

How the Use Classes Order and permitted development rights govern residential-to-HMO conversions, commercial-to-residential prior approval, and the new Use Class C5 for short-term lets.

14 min readUpdated 8 June 2026Last reviewed: 8 June 2026 by Richard Wood, Founderplanninghmochange-of-useuse-classes

Use Classes Relevant to Residential Landlords, C3, C4, and Sui Generis

The Town and Country Planning (Use Classes) Order 1987 (as amended) divides land uses into classes. The residential classes most relevant to landlords are: Use Class C3 (dwellinghouse, occupied as a single household); Use Class C4 (small HMO, 3 to 6 unrelated persons sharing amenities); and sui generis (large HMO, 7 or more persons). Changing from C3 to C4 is permitted development unless the LPA has made an Article 4 Direction removing this right. Changing from C3 or C4 to sui generis always requires planning permission.

  • C3 to C4 (small HMO, 3-6 people): permitted development unless an Article 4 Direction applies in the LPA area
  • C4 to C3 (HMO back to dwellinghouse): always requires planning permission, no permitted development right applies
  • C3 or C4 to sui generis (7+ HMO): always requires planning permission, no permitted development right exists
  • New Use Class C5 (short-term let) from May 2024: change from C3 to C5 requires planning permission in England
  • Article 4 Directions: LPAs in university cities widely remove C3-to-C4 permitted development rights, check before converting

Article 4 Directions, Removing HMO Permitted Development Rights

An Article 4 Direction removes specified permitted development rights in a defined LPA area. They are widely used by university-city LPAs to require planning permission for C3-to-C4 HMO conversions. In an Article 4 area, converting to a small HMO without planning permission is a breach of planning control. Large HMOs (sui generis, 7+ people) always require planning permission regardless of Article 4. The LPA must pay compensation if it refuses planning permission for C4 use solely because of the Article 4 Direction.

  • Check the Planning Portal Article 4 Direction map or contact the LPA before any HMO conversion
  • In Article 4 areas, planning permission is required for C3-to-C4 conversion; refusal on HMO concentration grounds is common
  • Article 4 compensation applies where the LPA refuses solely because of the Direction, not on substantive planning grounds
  • Large HMOs (sui generis) always require planning permission and are outside the Article 4 debate entirely

Prior Approval for Commercial to Residential, Class MA

Part 3, Class MA of the GPDO 2015 allows the conversion of Use Class E buildings (offices, shops, light industrial) to residential C3 use without a full planning application. The building must have been in Use Class E use for at least 2 years and vacant for at least 3 months before the application. The LPA can only assess specified matters (transport, contamination, flood risk, noise, natural light). A single application covers up to 1,500 sq m. If the LPA does not decide within 56 days of a valid application, the prior approval is deemed granted.

  • 2-year Use Class E use and 3-month vacancy are hard eligibility conditions for Class MA
  • LPA cannot refuse on grounds of loss of commercial floorspace or affordable housing requirements
  • 56-day default: LPA failure to decide within 56 days of valid application = deemed prior approval granted
  • Article 4 Directions can remove Class MA rights in high-demand commercial districts (City of London, central Manchester)

Use Class C5 and Short-Term Lets (Airbnb)

Secondary legislation under the Levelling-up and Regeneration Act 2023 created Use Class C5 (short-term let) from May 2024. Changing a C3 residential property to C5 (short-term let where the owner is not the principal resident) requires planning permission. In London, the Deregulation Act 2015 s.44 allows principal home owners to let for up to 90 nights per year without planning permission. LPAs in tourist hotspots (Cornwall, Lake District, Cotswolds) are expected to make Article 4 Directions removing the C3-to-C5 permitted development right.

  • Use Class C5 applies from May 2024 in England, change from C3 to C5 requires planning permission
  • London 90-night rule: principal home owners can let for up to 90 nights per year without planning permission
  • Investment properties let full-time as short-term lets in London require planning permission regardless of 90-night threshold
  • Tax FHL status and planning use class are separate, FHL tax registration did not mean planning permission existed
Primary sources

This page is drafted against the legislation below. Always check the current text of the law before acting.

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Reply to any LetSafe email or write to richard@letsafeuk.co.uk. We rewrite guides when we get something wrong, the sooner we hear, the sooner we fix it.

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