Buy-to-Let & Portfolio Mortgages for London Landlords

This page is for landlords buying, refinancing or expanding a buy-to-let portfolio in London — whether you hold one flat in your own name, run several properties across a few boroughs, or are moving toward a limited-company structure. London buy-to-let has its own affordability and regulatory pressures, and the search intent here is usually practical: can my case actually be placed, and who will lend on it.

Working across more than 135 lenders, Propertyze approaches London buy-to-let criteria-first: we work out who will lend at all on your property, your tax position and your structure before we worry about the headline rate, then present the case correctly so it stands the best chance of proceeding. The London market rewards that approach, because so many cases turn on detail rather than price.

Key facts at a glance

• The core test: lenders assess a buy-to-let on the Interest Coverage Ratio (ICR) — expected rent against the mortgage interest at a stressed (notional) rate, not the pay rate. Common thresholds are around 125% for basic-rate and limited-company borrowers and around 145% for higher- and additional-rate taxpayers. These are typical conventions, not fixed rules, and vary by lender.
• The London squeeze: London's high capital values relative to rents mean gross yields are often materially lower than in the North, which puts real pressure on rental cover — the central reason many London cases need careful placing.
• Two common routes through: a five-year (or longer) fix is often stressed more leniently, and top-slicing — using surplus personal or portfolio income — may help where rent alone is tight. Both are lender-dependent, not guaranteed.
• Stamp duty: the 5 percentage-point higher-rate surcharge for additional dwellings applies to most buy-to-let purchases (where the price is £40,000 or more), and on high London values that is a large cash sum to plan for. Figures here are general and may change at a future Budget.
• Portfolio landlords: holding four or more mortgaged buy-to-lets makes you a portfolio landlord under PRA standards, triggering whole-portfolio underwriting and a property schedule.
• Structure: many London landlords now buy through a limited company (SPV) — see our SPV buy-to-let page for how that works and its trade-offs.
• Regulation: most buy-to-let mortgages are not regulated by the FCA, though certain cases (for example a consumer buy-to-let, such as a property let to a close family member) can be regulated. We confirm which regime applies to your case.

The London yield reality — and how cases still work

The defining feature of London buy-to-let is the gap between capital values and rents. Because purchase prices are high relative to achievable rent, gross yields are often materially lower than in many northern markets. That matters because affordability is tested on rental cover, not on the property's value: the ICR test asks whether the rent, at a stressed interest rate, comfortably exceeds the mortgage interest with a buffer for voids, maintenance and rate movements. On a lower-yielding London property, the rent has more work to do to clear that bar — so the same loan that passes easily on a higher-yielding property elsewhere can be tight in London.

There are two well-established ways London cases still proceed. The first is the five-year (or longer) fixed rate. Where a product is fixed for five years or more, lenders commonly apply a more lenient stress rate — often at or near the actual pay rate rather than the higher notional rate used for shorter products — because a long fix removes payment-shock risk for that period. A longer fix can therefore support a larger loan on the same rent. The second is top-slicing, where a lender takes demonstrable surplus income — earned income, pension, or net profit from other rentals — into account to bridge a gap where the rent does not quite meet the ICR alone. Both routes are genuinely useful for London stock, but neither is universal: not every lender offers top-slicing, criteria differ, and relying on personal income means the property is less self-financing, so a change in your circumstances could leave you funding a shortfall. We assess which route, if either, fits your case.

A simple illustration shows why the threshold matters so much. On a £200,000 loan stressed at an illustrative 5.5%, a 145% ICR implies a required rent of roughly £1,329 a month; drop the threshold to 125% on the same loan and stress rate and the required rent falls to about £1,146. The difference — driven by tax status and structure — is often what decides whether a London case clears. These figures are illustrative only, not a quote or a live rate.

Stamp duty on a London buy-to-let

SDLT is frequently the largest single upfront cost on a London buy-to-let, simply because London prices are high. A surcharge of 5 percentage points sits on top of each standard SDLT band when you buy a property that means you will own more than one dwelling — which covers most buy-to-let purchases where the price is £40,000 or more. SDLT is charged on a slice basis, so each portion of the price is taxed at its band rate plus the surcharge. On a high-value London purchase, the higher bands carry the most weight, and the surcharge applies to companies as well as individuals — so an SPV purchase is not a way around it. A further 2 percentage-point surcharge applies where at least one buyer is non-UK resident, stacking on top of the rest.

The practical point is to budget for the full SDLT figure as cash at completion and factor it into your return from day one, rather than discovering it late. These rules are general and may change at a future Budget, and the exact figure depends on the price, your circumstances and how the purchase is structured; we will flag the SDLT position early so there are no surprises, though the precise calculation and any reliefs are matters for your conveyancer or tax adviser.

Licensing and Article 4 — the London regulatory layer

London adds a layer of local regulation that landlords elsewhere may not face, and it varies borough by borough. Mandatory HMO licensing applies to larger houses in multiple occupation across the country, but many London boroughs also operate additional HMO licensing (covering smaller HMOs) and selective licensing schemes (covering ordinary single-family lets in designated areas). Whether your property needs a licence depends on the specific borough and the scheme in force at the time, so it is worth checking the position with the local authority before you commit — both because operating without a required licence carries penalties and because some lenders take licensing into account.

Article 4 directions are the other London-specific issue. In parts of several London boroughs, an Article 4 direction removes the permitted-development right that would otherwise let you convert a family home (use class C3) into a small HMO (C4) without planning permission — meaning you would need a full planning application to do so. If your plan depends on converting to an HMO, the presence of an Article 4 direction can change the viability of the deal entirely. We factor licensing and planning realities into lender selection, because they affect both what you can legally do with the property and who will lend against that plan.

Regulation ahead — EPC and Section 21

Two regulatory changes are shaping landlord decisions and are worth planning around. The first is energy efficiency: the direction of travel is toward a minimum EPC rating of C for properties in the private rented sector, with C expected to become the required minimum across the sector by 2030. For older London stock — period conversions and mansion blocks in particular — the cost of reaching EPC C can be significant, and it is increasingly part of how landlords appraise a purchase and how some lenders view it. The second is possession: the planned abolition of Section 21 "no-fault" evictions changes how landlords regain possession, shifting toward defined grounds. Both are evolving areas; we keep the lending side aligned with where the rules are heading, but the detailed legal and timing position is one to confirm with a solicitor or your professional body, and the specifics may change as legislation progresses.

Structuring — personal name, SPV, and portfolios

How you hold a London buy-to-let increasingly drives both the tax outcome and which lenders will look at the case. Since full mortgage-interest tax relief was withdrawn for individual landlords (replaced by a basic-rate tax credit), higher- and additional-rate taxpayers carry a heavier effective tax cost on personally-held rental income — which is one reason limited-company (SPV) ownership has become common among London landlords, since a company can deduct mortgage interest as a business expense. It is also why the ICR threshold is commonly lower (around 125%) for company borrowers than the around 145% applied to higher-rate individuals. An SPV is not automatically the right answer — there are costs, complications and personal-circumstance factors involved, and the decision should be taken with proper tax advice — but it is a genuine planning point for London cases. Our SPV buy-to-let page sets out the trade-offs.

If you hold four or more mortgaged buy-to-lets you are a portfolio landlord under PRA standards, which means whole-portfolio underwriting: the lender assesses your entire portfolio, not just the property being financed, so an underperforming property elsewhere can affect an application. You will usually need a full property schedule and, depending on the lender, business plans and cash-flow statements. London portfolios — often a mix of leasehold flats with service charges and ground rents — reward a tidy, well-presented schedule. Our portfolio landlord page covers this in detail.

Common complications we handle

• Low-yield London flats that are tight on rental cover — placing the case with a lender whose stress approach (often a five-year fix) or top-slicing makes it work.
• Higher-rate taxpayers facing the around 145% ICR threshold on personally-held property, where structure and product choice make the difference.
• Limited-company (SPV) purchases and remortgages, including newly-formed SPVs and the directors'/shareholders' personal guarantee requirements.
• Portfolio landlords (four or more mortgaged BTLs) needing whole-portfolio underwriting, a property schedule and a coherent presentation across lenders.
• HMOs and properties in Article 4 or selective-licensing areas, where planning, licensing and lender appetite all interact.
• Leasehold flats with short leases, high service charges or cladding/EWS1 questions — common in London and a frequent sticking point for lenders.
• Ex-local-authority, high-rise or non-standard-construction stock, where lender criteria narrow sharply and the right match matters most.

The process

1. Initial conversation — we understand the property, the rent, your tax position and how you intend to hold it, and flag the likely affordability and SDLT picture early.
2. Criteria and structure check — we identify which lenders will consider the property and structure, and whether a longer fix, top-slicing or an SPV route helps the case.
3. Decision in principle — we approach a suitable lender and obtain an agreement in principle before you go further.
4. Full application and packaging — we package the case properly, including a portfolio schedule where you are a portfolio landlord, to give it the best chance.
5. Through to completion — we manage the case through valuation and the lender's process, working alongside your conveyancer to completion.

As a general guide you should expect to provide proof of identity and address, evidence of income and tax position, details of the property and expected rent, and — for portfolio or company cases — a property schedule and company documents. Timescales vary with the lender, the property and the conveyancing, so we will give you a realistic indication for your specific case rather than a fixed promise.

Frequently asked questions

Can a London buy-to-let pass the ICR test with such low yields? Often yes, but it needs the right approach. Lower yields make the rental cover test tighter, so London cases frequently rely on a five-year (or longer) fixed rate, which is commonly stressed more leniently, and sometimes on top-slicing. Whether your case passes depends on the rent, the loan, your tax status and the lender's criteria.

What is top-slicing? Top-slicing is where a lender uses surplus personal or portfolio income — earned income, pension or net rental profit from other properties — to support a case where the rent alone does not quite meet the ICR. It can help tight, lower-yielding London cases, but it is lender-dependent, the criteria vary, and it means the property is less self-financing.

Do I need an HMO licence for a London buy-to-let? It depends on the property and the borough. Larger HMOs need a mandatory licence nationwide, and many London boroughs also run additional HMO licensing and selective licensing schemes covering smaller HMOs and ordinary lets in designated areas. Check the position with the local authority before you commit.

How much stamp duty will I pay on a second London property? A 5 percentage-point surcharge applies on top of each standard SDLT band for an additional dwelling priced at £40,000 or more, charged on a slice basis, and a further 2 points apply for non-UK-resident buyers. On high London values this is a substantial cash sum. The figures are general and may change at a future Budget, and the exact amount and any reliefs are for your conveyancer or tax adviser to confirm.

Should I use a limited company (SPV) for a London buy-to-let? It can suit some landlords — particularly higher-rate taxpayers — because a company can deduct mortgage interest as a business expense, and company ICR thresholds are commonly lower than for higher-rate individuals. But there are costs and complications, and it is not automatically the right choice; take tax advice and see our SPV buy-to-let page for the trade-offs.

Speak to a specialist

Tell us about your London property and how you plan to hold it, and we will tell you, criteria-first, who is likely to lend and how to present the case. Call 020 7126 8574 or request a call back, and we will reply within one working day.

Your property may be repossessed if you do not keep up repayments on a mortgage secured on it.

Most buy-to-let mortgages are not regulated by the Financial Conduct Authority. Propertyze is a trading style of City Finance Brokers Ltd, authorised and regulated by the Financial Conduct Authority (FCA No. 766295). We conduct both regulated and unregulated business, so not all products provided through us are regulated by the FCA.