Commercial Buy-to-Let Mortgage: A Complete UK Guide

A commercial buy-to-let mortgage is a loan secured against a commercial property that the borrower intends to let to a business tenant. It is distinct from a residential buy-to-let mortgage, which finances dwellings let to private individuals, and from an owner-occupier commercial mortgage, which finances a property the business itself uses. The commercial buy-to-let product sits at the intersection of property investment and business lending — underwritten primarily on the strength of the rental income rather than the borrower's personal salary.

The commercial buy-to-let category covers a wide range of asset classes: retail units and shops, office suites, industrial units and warehouses, mixed-use buildings (commercial ground floor with residential flats above), large HMOs (houses in multiple occupation with five or more tenants), multi-unit freehold blocks, and specialist properties such as pubs or leisure premises. Each asset class carries its own risk profile in the eyes of a lender, which directly affects the maximum LTV available and the interest rate charged.

Commercial buy-to-let lending sits outside the residential mortgage framework entirely. Because lenders assess these loans on rental income and tenant covenant rather than on personal income multiples, the product is accessible to investors with complex income structures, retirees, and limited company borrowers — provided the rental arithmetic stacks on the property itself. This income-agnostic underwriting is one of the main reasons experienced property investors favour commercial assets when scaling a portfolio.

The lender advances a sum secured by a first legal charge over the commercial property. Repayments can be structured on an interest-only or capital repayment basis. Interest-only is the more common choice for investment properties because it maximises monthly cash flow, leaving rental surplus available for reinvestment or portfolio maintenance. Terms typically range from 5 to 25 years depending on the lender, the asset type, and the remaining lease length on leasehold properties.

Affordability is assessed using a rental coverage calculation. Most lenders require the gross annual rent to cover the annual interest cost by a factor of 125% to 145%, stress-tested at a notional rate typically 1–2% above the actual product rate. For example, on a £500,000 loan at 7.0% p.a., the annual interest charge is £35,000. At a 130% coverage requirement, the property would need to generate at least £45,500 in gross annual rent to satisfy the lender's minimum threshold.

Valuation underpins the entire process. Lenders instruct a specialist commercial valuer to assess the property on an investment yield basis — deriving the capital value from the annual rent divided by the prevailing market yield for that asset class and location. A retail unit generating £30,000 p.a. in an area where the market yield is 7.0% would be valued at approximately £429,000. This yield-based approach means that vacant or under-rented properties can value significantly below their estimated vacant possession value, which is a critical risk to manage when acquiring assets with rental uplifts in prospect.

Fees on a commercial buy-to-let mortgage typically include an arrangement fee of 1.0–2.0% of the loan amount, a commercial valuation fee (which scales with property value and complexity), legal costs for both borrower and lender, and where applicable a broker fee. All fees should be modelled against the rental income before committing to a product. For a full framework on comparing the all-in cost of different property finance products, see our guide to development finance vs bridging loans.

The minimum deposit for a commercial buy-to-let mortgage is typically 25–30% of the property value, meaning lenders will advance up to 70–75% LTV on mainstream commercial assets in good condition with strong tenant covenants. Specialist or higher-risk properties — pubs, petrol stations, single-tenant industrial units with short leases remaining — attract lower maximum LTVs of 55–65%, requiring deposits of 35–45%.

It is not possible to obtain a 90% LTV commercial buy-to-let mortgage from mainstream or specialist lenders. The commercial mortgage market operates with more conservative leverage than residential, reflecting the wider price volatility of commercial assets, greater variability of rental income, and the longer void periods that can occur when business tenants vacate. Some lenders will consider up to 80% LTV for mixed-use properties or multi-let industrial estates with several independent tenants, where income diversification reduces risk.

Where a borrower holds an existing portfolio with available equity, some lenders will accept a cross-charge over another property in lieu of a larger cash deposit, allowing the investor to leverage equity rather than raise fresh capital. This approach requires full disclosure and careful structuring, but it is a legitimate and widely-used method for investors who are asset-rich but liquidity-constrained.

Interest rates on commercial buy-to-let mortgages are not published on standardised comparison tables in the way residential mortgage products are. Pricing is largely case-specific, issued as a formal term sheet after a lender has reviewed the property details, tenant covenant, LTV, and borrower profile. That said, typical market rates in 2026 range from approximately 5.0% p.a. for the strongest assets at conservative leverage, to 9.5% p.a. or above for specialist properties or complex structures.

Products can be fixed or variable. Fixed rates — commonly for 3 or 5 years — provide certainty over monthly outgoings and are particularly popular where a long lease is in place with a creditworthy national tenant. Variable rates, typically expressed as a margin over the Bank of England base rate or SONIA, are more prevalent in the specialist lending market and may offer lower initial costs where rates are expected to fall. Early repayment charges (ERCs) apply on most fixed-rate commercial mortgages, so borrowers who anticipate selling or refinancing within the fixed period should negotiate ERC-free terms or a shorter initial fixed window before signing.

Loan terms range from 5 to 25 years. The maximum term a lender will agree depends on the property type, any remaining lease length on leasehold assets, and — for some lenders — the age of the borrower. Many specialist lenders apply no maximum age cap on commercial investment loans, assessing each transaction on its investment merits. Standard high-street lenders typically apply an age limit of 70–75 at the end of the mortgage term. A 60-year-old borrower could therefore obtain a 10–15 year term with most lenders, and potentially longer through specialist channels.

Arrangement fees are standardly 1.0–2.0% of the loan amount, payable on completion. Some lenders offer a lower headline rate paired with a higher fee; others do the reverse. The only accurate way to compare two products is to calculate the total cost of credit over the intended hold period — factoring in both the margin and all fees — rather than comparing headline rates in isolation. Our guide on bank versus specialist development finance covers this comparison methodology in detail and is equally applicable to commercial mortgage decisions.

Since the phased withdrawal of mortgage interest tax relief for individual landlords — fully in effect from April 2020 — most professional property investors acquiring new commercial buy-to-let assets do so through a limited company or a special purpose vehicle (SPV). The tax treatment differs materially between the two routes, and the right choice depends on the investor's marginal tax rate, existing portfolio structure, and intended hold period for the asset.

Commercial property is subject to non-residential SDLT rates, which differ from the residential rates and are not subject to the additional surcharge that applies to residential buy-to-let purchases by individuals. For mixed-use properties, SDLT is calculated on the non-residential scale, which can produce a meaningfully lower tax cost than an equivalent residential acquisition — a relevant factor when comparing asset classes within a portfolio.

Always take independent tax advice before selecting a borrowing structure. The correct answer changes significantly depending on whether you are an existing higher-rate or additional-rate taxpayer, whether you intend to extract profits or reinvest within the company, and whether the asset may ultimately pass to family members. A specialist broker can coordinate with your accountant to ensure the finance structure and the ownership structure are aligned from the outset.

Commercial buy-to-let lenders underwrite each loan against four primary factors: the property itself, the tenant covenant, the rental income relative to the debt cost, and the borrower's track record in property. Understanding each factor helps investors prepare a stronger application and reduces the risk of an unexpected decline or a late-stage renegotiation of terms.

The property must be in lettable condition and free from material structural defects, contamination, or unresolved planning issues. Single-purpose buildings — a car wash, a drive-through restaurant, a purpose-built filling station — are harder to finance on standard terms because their re-letting options are limited if the current tenant vacates. Multi-let assets and buildings with flexible use classes are generally viewed more favourably by lenders.

Tenant covenant is the second key variable, particularly for single-let assets. A long lease — typically 10 years or more unexpired — granted to a national or institutional tenant at a low LTV is the most straightforward scenario to finance. Short leases with fewer than five years to run, tenants trading on personal guarantees only, or assets that are currently vacant and being acquired for re-letting all introduce complexity that requires specialist lenders with the appetite and expertise for that risk profile. Borrower experience is assessed differently by different lenders: some require prior commercial property ownership, others accept experienced residential investors making a first commercial acquisition, provided a professional managing agent is appointed.

The application process begins with an indicative term sheet issued after a lender reviews an initial property summary and borrower information pack. Once terms are accepted, the lender instructs a commercial valuer and conducts due diligence on the tenant, the lease, and the title. Unlike development finance — which is drawn down in tranches against build progress — a commercial buy-to-let facility is advanced in full on day one of completion, so valuation and legal work need to complete before drawdown. Completion timescales typically range from 4–6 weeks for straightforward standard assets to 10–14 weeks for complex or multi-let properties. Working through a specialist commercial mortgage broker with access to a broad lender panel reduces the time spent on lender selection and significantly lowers the risk of a late-stage decline. Across Matt's career he has arranged commercial investment finance across every major asset class, and through Construction Capital works with over 100 lenders nationwide to source terms tailored to each investor's specific situation. If you are also weighing up how commercial debt compares to other capital structures, our guide to senior debt vs mezzanine finance provides a useful framework.