UK HMOs consistently deliver 8 to 12 per cent gross yields in strong Northern cities, but the licensing, planning, mortgage and management rules are materially tighter than standard buy-to-let. Here is what actually changes when you go HMO, with the specific traps investors miss.
Key Takeaways
- The Yield Case: HMOs typically produce 8-12% gross versus 5-7% for standard BTL apartments in the same cities.
- The Licence: Mandatory licensing applies to any HMO with 5+ occupants from 2+ households. Over 70 councils now also run additional licensing schemes.
- The Planning Trap: Article 4 Directions require full planning permission for C3 to C4 conversion. Present in many university city cores.
- The Mortgage Reality: Smaller lender pool, 25-40 per cent deposits, higher rates, and often prior landlord experience required.
What Counts as an HMO Under UK Law
Under the Housing Act 2004, a House in Multiple Occupation is a property occupied by three or more unrelated people forming two or more households, who share basic amenities such as a bathroom or kitchen. This is the core legal definition every landlord should know before doing any HMO calculation.
The Act also splits HMOs into two structural types. Section 254 HMOs are properties converted or adapted for HMO use, such as a family home turned into a shared house. Section 257 HMOs are self-contained flats originally built as a single dwelling but now split into separate lets. The compliance and licensing differences between the two matter for older converted properties.
HMO Licensing: Mandatory vs Additional
Mandatory HMO licensing applies nationally to any HMO occupied by five or more people from two or more households, following the Licensing of Houses in Multiple Occupation (Prescribed Description) (England) Order 2018. It applies regardless of the number of storeys, replacing the previous three-storey threshold.
Additional HMO licensing is discretionary under Section 56 of the Housing Act 2004. Local councils can designate schemes covering smaller HMOs, typically 3 or 4 occupants. Over 70 UK councils now run additional licensing schemes as of 2026, so treat "no mandatory licence needed" as the start of the check, not the end.
Selective licensing is a third scheme that covers all rented properties (not just HMOs) in specific council-designated areas. Some Manchester wards, Liverpool boroughs, and Birmingham areas operate selective licensing.
Quick FAQ:
Q: How much does an HMO licence cost?
A: Fees vary by council. Mandatory HMO licences typically range from £500 to £1,500 for a five-year term. Additional licences are usually slightly cheaper. Renewal is required every five years.
HMO Yields: The Real Numbers vs Standard BTL
A working example. A three-bedroom terrace in a strong Manchester or Birmingham suburb might buy for £220,000 and rent as a family home for £1,100 pcm — a gross yield of 6 per cent. Convert the same property to a five-bedroom HMO with three double bedrooms in the current three bedrooms plus two loft conversions, each let at £650 per room per month, and gross rent rises to £3,250 pcm — a gross yield of 17.7 per cent on the original purchase, or around 12 per cent after £75,000 of conversion and compliance costs.
Those numbers are illustrative, not universal. Actual HMO yields typically sit at 8 to 12 per cent gross once conversion costs, licensing fees, and higher void allowances are factored in. Well-run HMOs in university cities can push the top end of that range. Poorly-managed HMOs, or those in Article 4 zones with tenant demand ceiling, sit at the bottom.
Compare that against the standard buy-to-let apartment story in the same cities: 5 to 7 per cent gross, lower operational overhead, but a materially lower income base to work with. Both models can work. The choice depends on your risk appetite, hands-on availability, and starting capital. Use the rental yield calculation guide to model your own numbers before committing.
Article 4 Directions: The Planning Trap
An Article 4 Direction is a planning tool that lets a local authority withdraw permitted development rights in a specific area. In HMO terms, converting a C3 (family) property to a C4 (small HMO, 3-6 occupants) inside an Article 4 zone requires full planning permission rather than being automatic.
This matters because Article 4 zones exist in the areas where HMOs traditionally work best: university city cores. Manchester's Fallowfield and Withington, Liverpool's Kensington and L15, Nottingham's Lenton, and Newcastle's Heaton have all had Article 4 directions in place for years. Some councils have expanded these to cover entire wards.
Practical implication: check the specific street's planning status before you offer. A property that looks like a straightforward HMO conversion on paper can be a full-planning-application process taking six to nine months, with no guarantee of approval.
Quick FAQ:
Q: Can I still buy an existing HMO inside an Article 4 zone?
A: Yes. Article 4 restricts new conversions. Properties already lawfully operating as HMOs retain their use class, and can be bought and continued as HMOs. The trap is converting a new-to-you family house inside the zone.
HMO Mortgages and Set-Up Costs
Standard buy-to-let mortgages generally do not accept HMO properties. HMO-specific products come from a smaller lender pool, and typically require:
- Deposit of 25 to 40 per cent, versus 20-25 per cent on standard BTL
- Higher rates and arrangement fees than standard BTL products
- Prior landlord experience, with many lenders requiring at least one existing BTL for two years before considering HMO lending
- Property meeting minimum room-size and licensing standards at drawdown, not just at intended-use point
Set-up costs beyond the deposit: HMO licence fee, room-size upgrades, fire safety compliance (fire doors, hard-wired alarms, emergency lighting), extra kitchen equipment, and often an initial furnishings package. Budget £15,000 to £40,000 for a full conversion of a three-bed family home to a five-bed HMO, on top of the purchase price.
Also worth factoring: Section 24 mortgage interest restrictions apply to HMOs just as they do to standard BTL. Combined with the higher HMO mortgage rate, that hits net yield harder than the gross rent numbers suggest.
Should You Actually Go HMO
The right question is not "will an HMO make more money" — usually yes, on gross. The right question is whether the extra work, cost, and risk are the right fit for you.
HMOs make sense if you:
- Have hands-on availability or a management partner you trust
- Can commit to 5-year licensing cycles and ongoing compliance
- Are buying in a proven tenant-demand area (university, hospital, city centre)
- Have £15-40k of conversion capital beyond the deposit
Standard BTL makes sense if you:
- Prefer lower operational load and simpler tax accounting
- Want to build a portfolio using standard, mainstream mortgages
- Are targeting long-term capital growth over maximum income
- Are new to landlording — see our First-Time BTL guide
The Bottom Line
HMOs are a legitimate high-yield play, but they are not a shortcut. Licensing, Article 4, mortgage restrictions, and higher management overhead all bite the gross yield hard. Model the net numbers carefully. If the math works and you can commit to the operational demands, HMOs in the right Northern city can deliver 8 to 12 per cent gross. If any of those preconditions is fragile, a well-priced standard BTL in the same market is usually the safer capital allocation.
Disclaimer: This article is for general information only. Rothmore Property is not a licensing authority, mortgage broker, or planning consultant. Licensing rules, planning designations, and mortgage terms vary by local authority and lender. Consult the specific council and a qualified specialist before committing to any HMO acquisition or conversion.
