Not every unlicensed HMO involves a large shared house. Many London boroughs run additional licensing schemes that extend licensing requirements well below the national five-person threshold — which means ordinary flat-shares that tenants wouldn't normally think of as an "HMO" can still require a licence.
What Is Additional Licensing?
Under section 56 of the Housing Act 2004, a council can designate all or part of its area for additional licensing, applying licensing rules to smaller HMOs that fall outside the mandatory national scheme. The threshold is set locally, and it varies significantly between boroughs.
In Hackney and Islington, for instance, additional licensing can catch a property with just three occupants from two households — meaning a small two-bedroom flat shared by three friends could legally require a licence, even though it would fall well short of the national mandatory threshold.
Why This Matters for Tenants
Because the threshold is so much lower, additional licensing offences are common — and often go unrecognised by tenants who assume licensing only applies to larger shared houses. If your landlord didn't hold the required additional licence, that's a criminal offence and qualifies you to apply for a Rent Repayment Order, exactly as with mandatory HMO or selective licensing offences.
Checking Your Borough's Scheme
- Additional licensing thresholds and coverage areas are set by each council individually, so what applies in one borough may not apply next door.
- Check your council's public HMO licence register for your specific address.
- If in doubt, we check this for free across all ten boroughs we cover, including Islington's borough-wide additional licensing scheme.
What You Could Claim
The same principles apply as any other licensing offence: up to 12 months' rent, no need to prove financial loss, and no need for a criminal conviction against your landlord. See our full guide to RRO amounts for how the Tribunal decides how much to award.