Semi-commercial, or mixed-use, property, a retail unit with flats above being the classic example, sits between residential buy-to-let and full commercial investment. This guide covers the single variable that most investors underestimate, the commercial-to-residential split, along with rates, LTV, affordability testing, and a genuine stamp duty advantage most buyers don't realise applies.
Figures below reflect published 2026 commercial broker guidance, current to mid-2026. This is general education, not financial advice; commercial and semi-commercial mortgage criteria are genuinely lender-specific and change, so get quotes from a specialist broker before proceeding.
1. What counts as semi-commercial
Most UK lenders require the residential element of a property to make up at least around 40% of the floor area or rental value before treating it as semi-commercial rather than fully commercial. A shop with a flat above, or an office with residential units on upper floors, are the classic examples. Below that residential threshold, the property is generally assessed under standard commercial property criteria instead, a meaningfully different lending framework.
2. Why the split matters more than almost anything else
Lenders measure the commercial-to-residential split by floor area in most cases, occasionally by assessed value instead, and this single number determines which lenders will even consider the deal. A property that's around 70% residential by floor area can often access specialist lenders whose semi-commercial products sit close to their buy-to-let range, benefiting from more favourable pricing. A property that's 70% commercial is assessed on standard commercial property criteria instead, typically meaning a higher rate and a more conservative maximum loan-to-value. Getting a valuer's apportionment of the split early in the process is genuinely important, since it determines which lenders will actually compete for the deal.
3. Rates and LTV in 2026
| Metric | Typical range in 2026 |
|---|---|
| Maximum LTV | 65% to 75%, occasionally 75-80% for strong cases (long leases, experienced borrowers, prime locations) |
| Typical deposit | 25% to 35% |
| Indicative rate | Roughly 5.5% to 8%, depending on LTV, the commercial/residential split, property condition, and borrower profile |
| Term length | 5 to 25 years, occasionally up to 30 |
With the Bank of England base rate at 3.75% for much of 2026, semi-commercial mortgage rates have typically started from around 2.5 percentage points above base rate for straightforward cases, with higher-risk trades (restaurants, takeaways, and similarly higher-turnover commercial units) or weaker commercial leases pushing rates and deposit requirements higher still.
4. How affordability is actually tested
For an investment purchase, combined rental income from the residential units and the commercial unit typically needs to cover 125% to 145% of the mortgage payment, stress-tested at an assumed interest rate of around 6% to 7%, regardless of the actual rate you're being offered. This is a materially more conservative test than many residential buy-to-let calculations, reflecting the genuinely higher risk profile lenders attach to a commercial income component.
5. EPC risk is now priced into the deal
Lenders are increasingly pricing EPC risk into semi-commercial lending decisions, and properties with an EPC F or G rating on the residential portion face a genuinely narrower panel of willing lenders and less favourable rates and LTV. Budgeting for energy efficiency improvements before applying, our EPC Improvements guide covers what actually moves the rating, can meaningfully broaden the pool of lenders willing to compete for the deal.
6. The stamp duty advantage
Mixed-use property is taxed under non-residential Stamp Duty Land Tax rates rather than residential rates, since it isn't classified as a purely residential dwelling. This means a genuine cost advantage: mixed-use purchases aren't subject to the additional dwelling surcharge that applies to most second and investment residential properties, nor the non-UK resident surcharge, both covered in full in our Stamp Duty Timeline. For an investor who might otherwise face these surcharges on a purely residential purchase, this is a genuinely significant, and frequently overlooked, part of the overall return calculation.
7. Documentation you'll need
- Full property details for both the shop and each flat, including size in square metres, current rent if let, and occupancy status.
- Copies of any existing tenancy agreements for the residential units.
- The commercial lease, or heads of terms if a new lease is being agreed for the commercial unit.
- Evidence of your income: payslips and P60s for employed income, tax calculations for self-employed income, or company accounts if you trade from the premises yourself.
- Details of your deposit source and evidence of funds.
8. Frequently asked questions
What counts as semi-commercial property?
Most UK lenders treat a property as semi-commercial, or mixed-use, where the residential element makes up at least around 40% of the floor area or rental value, a shop with a flat above being the classic example. Below that threshold, the property is generally assessed as fully commercial instead.
Does the commercial-to-residential split really change my mortgage rate?
Yes, significantly. A property that's around 70% residential by floor area can often access specialist lenders whose semi-commercial products sit close to their buy-to-let range, while a property that's 70% commercial is assessed on standard commercial property criteria, which typically means a higher rate and a more conservative maximum loan-to-value.
Is stamp duty lower on a semi-commercial property than a residential one?
Generally yes. Mixed-use property is taxed under non-residential Stamp Duty Land Tax rates rather than residential rates, which means it isn't subject to the additional dwelling surcharge or the non-UK resident surcharge that apply to purely residential purchases, a genuine and often overlooked cost advantage.
Does the EPC rating of the residential part affect a semi-commercial mortgage?
Yes. Lenders are increasingly pricing EPC risk into semi-commercial lending, and properties with an EPC F or G rating on the residential element face a narrower panel of willing lenders and less favourable rates. Budgeting for energy efficiency improvements before applying can broaden the available lender panel.
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