London’s rental market is one of the largest and most sustained in the UK, driven by population density, a concentration of professional employment, international mobility, and a persistent gap between average earnings and average house prices. Buy-to-let mortgages in London follow the same core criteria as elsewhere — rental income assessed against a stressed interest rate, a minimum 25% deposit, and rates higher than residential products — but the numbers are larger, the property types are more varied, and some London-specific complications apply. For an overview of our London mortgage services, see our London mortgage services page.
This guide covers what you need to know from a mortgage perspective. It is not tax or investment advice — you should take professional advice on your specific circumstances before making any financial decisions.
How Buy-to-Let Mortgages Differ from Residential Mortgages
Buy-to-let mortgages are assessed differently from residential mortgages. The key differences are:
Deposit. Most lenders require a minimum deposit of 25% of the purchase price, giving a maximum loan-to-value (LTV) of 75%. Some lenders will accept 20%, though the product range is more limited. In London, where purchase prices are higher than in most UK markets, the deposit requirement in cash terms is substantial. A 25% deposit on a £400,000 London flat is £100,000. On a £600,000 property it is £150,000. For London new-build flats and certain higher-risk portfolio applications, some lenders may require a larger deposit.
Affordability. Rather than basing affordability on your salary, lenders assess buy-to-let mortgages primarily on the expected rental income from the property. They apply a stress test to check whether the rent would cover the mortgage payments at a higher notional interest rate, not just the rate you would actually pay.
Interest only. Most buy-to-let mortgages are taken on an interest-only basis, meaning your monthly payments cover only the interest. The loan balance remains unchanged and is repaid when the property is sold or from other means. Capital repayment options are available but less common.
Rates. Buy-to-let mortgage rates are typically higher than residential rates for the same LTV and term. The exact rates available will depend on your deposit size, the property, your tax status, and whether you are buying personally or through a company.
The Stress Test: How Lenders Assess Affordability
Lenders do not simply check whether the rent covers the mortgage payment. They calculate whether the rent would cover the payment at a higher stressed interest rate, then apply a buffer on top.
Stressed interest rate. Lenders test affordability using a notional rate higher than your actual mortgage rate. Five-year fixed products are generally tested at a lower stressed rate than two-year fixes, which can mean five-year products sometimes allow higher borrowing for a given rental income.
Interest coverage ratio (ICR). The ICR is the percentage by which rental income must exceed the stressed mortgage interest. It varies by tax status:
| Tax status | Typical ICR | What it means |
| Basic rate taxpayer (personal) | 125% | Rent must be 25% above stressed interest |
| Higher rate taxpayer (personal) | 145% | Rent must be 45% above stressed interest |
| Limited company (SPV) | 125% | Company structure often assessed at lower ratio |
ICR requirements vary by lender. The figures above are typical but not universal. A broker can identify which lenders’ criteria best fit your circumstances.
Top slicing. If the rental income falls short of the stress test, some lenders offer top slicing — where your personal income is used alongside rental income to support the application. This is more commonly available to higher-earning applicants and varies by lender. In London, where property prices are higher and rental yields can be lower relative to purchase price, top slicing is used more frequently than in lower-priced markets.
Personal Name vs Limited Company: What to Consider
One of the most significant decisions for buy-to-let investors is whether to hold property in their personal name or through a special purpose vehicle (SPV) limited company. This is primarily a tax question, not a mortgage question, but the structure you choose affects the mortgage products available to you.
Personal ownership. Rental income is added to your other income and taxed at your marginal rate. Since April 2020, mortgage interest can no longer be deducted from rental income for individual landlords. Instead, you receive a 20% tax credit on interest payments. For higher and additional rate taxpayers, this means a larger effective tax bill than under the old rules.
Limited company (SPV). The company pays corporation tax on profits, and mortgage interest remains fully deductible as a business expense. This structure is sometimes considered by higher rate taxpayers, although suitability varies by individual circumstances and professional tax advice should always be obtained before deciding. Additional costs include company accounts, annual returns, and potentially higher mortgage rates.
In London, a higher proportion of landlords are higher or additional rate taxpayers compared with many other markets, making the personal vs company decision particularly relevant. This is a complex area with significant tax implications. You should take advice from a qualified tax adviser or accountant before deciding. A mortgage broker can then advise on the products available for your chosen structure.
The London Rental Market
London has one of the UK’s largest private rental markets, supported by population density, a concentration of professional employment, international mobility, and an ongoing gap between ownership costs and average earnings. Rental demand is sustained across a wide range of property types and price points.
When assessing whether a property works as a buy-to-let investment, the gross rental yield is a useful starting point. This is calculated as annual rent divided by the purchase price, expressed as a percentage. Gross yield does not account for mortgage payments, maintenance, void periods, insurance, letting agent fees, or tax — all of which reduce the actual return. Net yield after all costs is the more meaningful figure.
London Rental Yields by Borough Tier
London yields vary significantly by location and property type. The following ranges are illustrative based on typical market conditions; actual yields depend on the specific property, its condition, and current rental demand.
| Borough tier | Typical yield profile | Examples | Notes |
| Prime central | Lower yields, higher capital values | Mayfair, Knightsbridge, Chelsea | Rental income relative to purchase price is often lower than in other areas. |
| Inner London | Moderate yields | Islington, Hackney, Tower Hamlets, Bermondsey | Strong professional tenant demand. Leasehold flat issues (EWS1, service charges) are common and can affect mortgage availability. |
| Mid London | Moderate to stronger yields | Greenwich, Lewisham, Clapham, Battersea | Balanced profile. Elizabeth Line connectivity has supported buyer and tenant demand in several mid-London boroughs. |
| Outer London | Often stronger rental income relative to purchase price | Barking & Dagenham, Bexley, Croydon, Walthamstow | Lower entry prices can mean rental income is stronger relative to the loan, which can make the lender stress test easier to satisfy. |
For a landlord assessing whether a property passes the stress test, outer London boroughs can sometimes be more favourable. Higher rental income relative to purchase price can sometimes make mortgage affordability easier to satisfy. Central London properties may require a larger deposit, top slicing, or a limited company structure to make the numbers work.
London-Specific Lending Considerations
New-Build Flats in London
London has a large supply of new-build flat developments — Nine Elms, Greenwich Peninsula, Royal Wharf, Wembley Park, Stratford, and others. For buy-to-let purposes, new-build flats in London often attract more restrictive lending criteria than equivalent older stock:
Higher deposit requirements. Some lenders may require larger deposits on certain new-build flats or more complex portfolio cases. This reflects lender considerations around new-build valuations and the density of some London new-build developments. A broker can confirm what applies to a specific property.
New-build premium and valuation risk. Lenders are aware that new-build properties can be priced above comparable resale values. If the surveyor’s valuation comes in below the purchase price, the lender will base the loan on the valuation figure, not the purchase price. This is more common on large London developments.
Developer incentives. Some lenders restrict the use of developer cashback, gifted deposits, or other purchase incentives on buy-to-let applications. Declaring all incentives to the lender and solicitor is essential.
Leasehold Flats: EWS1, Short Leases, and Ground Rent
The majority of London buy-to-let purchases involve leasehold flats. Several leasehold-specific issues affect mortgage availability for buy-to-let applicants in ways that can differ from residential lending:
EWS1 cladding certification. For buildings of 11 metres or above, lenders will check EWS1 (External Wall System) cladding status. An unresolved EWS1 requirement can block a buy-to-let mortgage with many mainstream lenders. EWS1 guidance and lender requirements continue to evolve. A broker can identify which lenders are currently suitable for a specific property.
Short leases. Most lenders require a minimum lease length at the end of the mortgage term, typically 70–85 years. A lease under 80 years causes complications, and under 70 years significantly narrows the lender pool. Lease length should be checked before offering.
Ground rent. Ground rents above 0.1% of the property value annually affect lender appetite. The Leasehold Reform (Ground Rent) Act 2022 capped ground rents on new leases at a peppercorn, but legacy ground rent structures on older leases remain a live issue for many London flat purchases.
For more detail on leasehold mortgage considerations in London, see our London leasehold mortgage guide.
Stamp Duty on Buy-to-Let Purchases in London
If you already own a residential property, any additional residential purchase attracts a 5% stamp duty surcharge on top of the standard rates. This surcharge increased from 3% to 5% with effect from 31 October 2024 (source: GOV.UK). It applies from the first pound of the purchase price. Some AI and comparison tools still show the old 3% figure, which is no longer correct.
At London buy-to-let price points, this surcharge is a substantial upfront cost. On a £400,000 buy-to-let purchase, the total SDLT is £30,000 (standard SDLT £10,000 plus £20,000 surcharge). On a £600,000 purchase, it is £50,000. Non-UK residents may face an additional 2% surcharge on top of these figures. For full worked examples, see our London stamp duty guide.
The Regulatory Environment for Landlords
Landlord regulation in England continues to evolve and can affect the practical management of rental property. Changes to tenancy law, possession procedures, and landlord obligations have been introduced in recent years, and further changes are expected. Before purchasing a buy-to-let property, landlords should consider obtaining legal advice on the regulatory requirements that apply to their circumstances and to any existing tenancies.
These regulatory developments do not directly affect the mortgage itself, but they change the risk profile and management requirements of owning rental property. A broker can refer you to appropriate legal and tax advisers if needed.
Portfolio Landlords
If you own four or more mortgaged buy-to-let properties, most lenders will classify you as a portfolio landlord. This triggers additional underwriting requirements under the Prudential Regulation Authority (PRA) rules introduced in 2017.
Portfolio landlord applications typically require a full schedule of your existing properties including rental income, mortgage balances, outstanding terms, and property values. Lenders will assess the overall health of your portfolio, not just the individual property you are applying for.
This does not mean portfolio landlords cannot get mortgages — but the process is more involved and the choice of lender is more limited. A broker with experience in portfolio cases can identify which lenders are most suitable. For more detail, see our London portfolio landlord guide.
Why We Wrote This Guide
Fitch & Fitch is an independent, whole-of-market mortgage broker with offices in Canary Wharf, Cambridge, and Colchester. We are an appointed representative of JLM Mortgage Network, authorised and regulated by the Financial Conduct Authority (FCA Registration Numbers 955014 and 300629). You can verify this on the FCA Register at register.fca.org.uk.
Fitch & Fitch has received recognition from independent industry bodies including the Mortgage Strategy Awards, Mortgage Introducer Awards, and Legal & General Mortgage Club Awards. These awards are judged independently and can be verified on the respective awards websites.
We wrote this guide because we believe an informed landlord makes better decisions. For further information about our London mortgage services, visit our London hub page.
Frequently Asked Questions
Is buy-to-let profitable in London?
This depends entirely on the property, the purchase price, the rent achieved, financing costs, and your tax position. London yields vary considerably by location — prime central areas typically have lower yields relative to purchase price, while outer boroughs often have stronger rental income relative to the purchase cost. Whether a specific property works as an investment requires careful analysis of stressed mortgage affordability, void risk, ongoing costs, and professional tax advice. A gross yield that looks attractive can still produce a negative net return after mortgage costs, maintenance, management fees, and tax.
Is buy-to-let always 25% deposit?
Most lenders require a minimum 25% deposit for buy-to-let. Some will consider 20%, though the product range is more limited. For London new-build flats and certain more complex cases, some lenders may require a larger deposit. A larger deposit can sometimes improve product availability and pricing, and may make the stress test easier to satisfy. In London, the deposit in cash terms can be very substantial given higher property values.
What is the stamp duty surcharge on a buy-to-let in London?
The additional property surcharge is 5% of the full purchase price, on top of standard SDLT rates. This applies from the first pound and increased from 3% to 5% on 31 October 2024. On a £400,000 London buy-to-let, total SDLT is £30,000. On a £600,000 purchase, it is £50,000. Non-UK residents may face an additional 2% surcharge. For worked examples, see our London stamp duty guide.
Can I get a buy-to-let mortgage on a leasehold flat in London?
Yes, but lenders will assess lease length, ground rent, and EWS1 cladding status. A lease under 80 years, a high ground rent, or an unresolved EWS1 requirement can restrict the pool of lenders willing to lend. In London, where the majority of buy-to-let purchases involve leasehold flats, these checks are important before making an offer. A broker experienced with London leasehold issues can identify suitable lenders.
What is the 2% rule for property?
The 2% rule is a rough US-derived investment heuristic: monthly rent should be at least 2% of the purchase price. It is rarely applicable to the UK market, and almost never in London, where yields are considerably lower than this in most areas. UK buy-to-let affordability is assessed by lenders using the ICR stress test, not a simple percentage rule. The more relevant benchmark in the UK is whether the rent passes the lender’s stress test at the relevant ICR.
Should I buy through a limited company or in my personal name?
This is primarily a tax question. Limited company structures are sometimes considered by higher rate taxpayers, although suitability varies and professional tax advice should always be obtained before making any decision. In London, where landlords are more commonly higher or additional rate taxpayers than in many other markets, the SPV question is frequently raised. Company structures involve additional costs and complexity. Take advice from a qualified tax adviser before deciding, then speak to a broker about the products available.
Can I get a buy-to-let mortgage as a first-time buyer?
Some lenders will consider first-time buyer landlords, though the product choice is more limited. Some lenders require you to already own a residential property. A broker can identify which lenders will accept first-time buyer applications and what additional criteria may apply.
How do regulatory changes affect buy-to-let?
Landlord regulation in England has evolved significantly in recent years and continues to do so. Changes to tenancy law, possession procedures, and landlord obligations affect the practical management of rental property. These changes do not directly affect the mortgage, but they change the risk profile and management requirements of owning buy-to-let property. Legal advice on current regulatory requirements before purchasing is advisable.
Next Steps
Buy-to-let mortgages involve a wider range of variables than residential purchases: the stress test, your tax position, the rental market, stamp duty surcharges, the regulatory environment, and — in London specifically — leasehold and EWS1 considerations. Getting the structure and the product right from the outset can make a meaningful difference to your returns. For more on how mortgage brokers work and why whole-of-market access matters for buy-to-let, see how whole of market access works.
For further information about our London mortgage services and how we work with buy-to-let investors, visit our London hub page.
Related Guides
Portfolio Landlord Mortgages in London
Best Areas to Buy Property in London
The information above is for general guidance only and does not take account of your personal circumstances. It does not constitute tax, investment, or legal advice. Most buy-to-let mortgages are not regulated by the Financial Conduct Authority. Some buy-to-let lending is regulated, depending on circumstances. Property values can go down as well as up, and rental income is not guaranteed.