A broker’s guide to semi-commercial buy-to-let lending

The UK property market is always shifting, and as a broker, your ability to guide your clients toward high-performing asset classes is exactly what sets you apart. As the market evolves toward more professional portfolio landlords, your clients are seeking to invest in properties that can offer higher yields and returns through HMOs and MUFBs. 

According to market forecasts, total UK commercial property lending is on a sharp upward trajectory, projected to climb from £90 billion in 2023 to a staggering £118 billion by 2028.

A massive driver of this broader commercial growth is the semi-commercial sector, which is rapidly gaining popularity among seasoned and expanding investors alike. The continuous growth highlights a profound and sustained shift in the industry:

• Sustained volume growth: Following a massive year in 2024, where total applications doubled compared to 2023 data, the momentum has surged even further. Applications for semi-commercial properties climbed by another 58% in the first half of 2025 compared to the same period in 2024.

• Increasing portfolio and market share: By the end of 2024, semi-commercial applications accounted for an impressive 24% of all commercial lending activity. This footprint has only solidified, with semi-commercial purchase applications rising by 31% year-on-year as a proportion of all specialist lending applications, proving that the asset class is a permanent fixture of modern portfolio design rather than a passing trend.

• The dominant popularity mix: Within the semi-commercial sector, retail units with residential flats above remain the undisputed favourite, making up 69% of all mixed-use applications (up from 60% previously).

Why are property investors shifting their capital into this specific niche so aggressively? From a strategic standpoint, it boils down to two major structural advantages:

• Dual income potential: Investors are highly attracted to the ability to generate two distinct streams of rental income from entirely different types of tenants, all secured under one single title.

• Favourable tax treatment: These mixed-use assets frequently enjoy highly advantageous tax treatments, particularly in relation to Stamp Duty Land Tax (SDLT), which drastically improves the entry economics and ongoing profitability for buyers.

Understanding the asset: What qualifies as semi-commercial?

Now that we see exactly why demand is surging, let's clearly define what constitutes a semi-commercial property under our lending guidelines.

In simple terms, a semi-commercial property is a mixed-use asset that typically comprises a residential property located directly above commercial space. However, to qualify for our new product range, the property must adhere to several structural and operational rules:

• Independent operations and separate access: The property must possess completely separate access points for both the residential and commercial elements. This structural requirement ensures that both parts of the building can operate independently of each other without shared entryways.

• A single freehold title: Even though the two elements function completely independently, both the commercial space and the residential units must be held on a single freehold title.

The dual nature of the property is also reflected in how the tenancies are managed:

• Residential tenancies: The residential component of the property is normally let out to tenants utilising a standard Assured Shorthold Tenancy (AST) agreement.

• Commercial leases: The ground floor or trading business element operates under a traditional commercial lease.

Underwriting considerations and advisory framework

For mortgage advisers and brokers evaluating semi-commercial opportunities for portfolio clients, navigating the underwriting process requires a thorough understanding of how commercial and residential elements interact. Because these assets bridge two distinct market sectors, credit assessment and risk management principles differ significantly from standard residential buy-to-let transactions.

1. Affordability assessment and income stress testing

Unlike standard buy-to-let properties where affordability relies predominantly on residential rental coverage, semi-commercial affordability assessments require evaluating two independent revenue streams:

• Residential income streams: Residential rents are evaluated using Interest Coverage Ratio (ICR) stress tests, typically benchmarked between 125% and 145% depending on whether the applicant is an individual, higher-rate taxpayer, or SPV limited company.

• Commercial income streams: Commercial lease income undergoes rigorous scrutiny. Underwriters evaluate the financial health and trading history of the commercial tenant, lease duration, break clauses, and sector longevity. Commercial rental income is often subjected to higher ICR thresholds or Debt Service Coverage Ratio (DSCR) standards to account for potential vacancy periods.

• Proportional income weighting: Lenders typically assess the split between commercial and residential income. When the residential element accounts for the majority of the total property value or income (often over 50%), the asset qualifies for more streamlined specialist lending options. Conversely, commercial-heavy assets are usually underwritten via traditional commercial terms.

2. Valuation methodologies for mixed-use assets

Valuing a semi-commercial asset involves dual valuation approaches that mortgage advisers must understand when advising clients on maximum borrowing capacity:

• Vacant possession vs. investment yield: Residential units are generally valued on a vacant possession basis using comparable local residential sales. Commercial elements are primarily valued on an investment yield basis, taking into account current market yields, tenant strength, and lease length.

• Impact of commercial use on residential value: Valuers carefully assess whether the nature of the commercial business (such as late-night food outlets, licensed premises, or noisy industrial activities) negatively impacts the resale value or tenant demand for the upper residential flats.

• Access and title integrity: Valuers and legal teams must confirm that independent access to the residential units is physically established and that both components operate under a unified single freehold title.

3. Commercial lease mechanics and due diligence

To ensure smooth processing, advisers should review key commercial lease features prior to application submission:

• Security of tenure: Advisers must determine whether the commercial lease is 'inside' or 'outside' the protection of the Landlord and Tenant Act 1954. A lease inside the Act gives the commercial tenant statutory rights to renew, offering income stability but limiting the landlord's flexibility for future redevelopment.

• Unexpired lease term: Lenders prefer commercial leases with sufficient remaining unexpired terms (often requiring at least 3 to 5 years remaining beyond completion) to ensure rental stability.

• Lease structure (FRI vs. internal repairing): Full Repairing and Insuring (FRI) leases require the tenant to cover building maintenance, repairs, and insurance costs, resulting in higher net yields and lower ongoing operational expenditure for the landlord investor.

4. Tax efficiencies and SDLT considerations

A primary catalyst driving client interest in semi-commercial property is the advantageous tax structure:

• Stamp Duty Land Tax (SDLT) advantage: Mixed-use properties attract non-residential SDLT rates in England and Northern Ireland. Because non-residential SDLT rates top out at lower percentage thresholds compared to residential property rates (and avoid the additional residential surcharge), investors often realise substantial upfront tax savings on acquisition.

• Corporate ownership benefits: Holding semi-commercial assets within a limited company structure allows full deductibility of finance costs as a business expense, mitigating the tax restrictions introduced for individual property investors.

Empowering your clients

By bringing the market's growth story to the forefront, it becomes incredibly clear to see why this asset class is dominating investor conversations. This new semi-commercial product gives you an exceptional tool to help your clients expand their portfolios, optimise their tax positions via favourable SDLT structures, and capture reliable dual-income streams. Review the criteria, identify the clients in your pipeline who stand to benefit, and let’s work together to fund their next big property acquisition or remortgage.