Buy-to-Let Mortgage Guide UK 2026 — Criteria, Rates, and Portfolio Landlord Rules

BTL mortgage criteria — deposit, LTV, and rental coverage stress tests

The core BTL mortgage criteria centre on the deposit (and therefore LTV) and the rental income relative to the mortgage payment at a stress test rate:

• Minimum deposit — typically 25% (75% LTV): Most BTL lenders require a minimum deposit of 25% of the property's purchase price or value — equivalent to a maximum loan-to-value (LTV) of 75%. Some specialist lenders offer BTL mortgages at 80% LTV (20% deposit) for lower-risk properties and experienced landlords, but the rates are significantly higher. New landlords with no previous BTL experience may find they are restricted to 70%-75% LTV by some lenders. The 25% deposit requirement also applies on remortgage — if the property has declined in value, the landlord may not meet the 75% LTV test on remortgage and may be unable to switch lenders. The property must typically be valued by the lender's approved surveyor
• Rental coverage ratio — stress testing at 125%-145%: Lenders require that the monthly rent achievable for the property exceeds the monthly mortgage payment by a coverage ratio of between 125% and 145%, calculated at a stress test interest rate rather than the actual mortgage rate. The stress test rate is typically 5.5%-6.5% (set by each lender above the Bank of England base rate, regardless of the actual fixed rate offered). For a £200,000 mortgage, the lender stress tests the monthly interest payment at e.g. 5.75% pa (£958/month) and requires the monthly rent to be at least 125% of that figure (£1,198/month). This means the headline rental yield must comfortably exceed the stress-tested mortgage payment — a constraint on higher LTV borrowing in lower-yield markets
• Higher-rate taxpayer rental coverage ratio: PRA guidance from 2017 requires lenders to apply a higher rental coverage ratio (typically 145% rather than 125%) for higher-rate taxpayer landlords borrowing in a personal name. This reflects the impact of the Section 24 finance cost restriction on higher-rate taxpayer landlords' net rental income. A lender may apply 125% for a basic-rate taxpayer and 145% for a higher-rate or additional-rate taxpayer — for the same property and mortgage amount. Limited company (SPV) borrowers typically qualify for the 125% coverage ratio regardless of the director's personal tax rate, because the company is the borrower and benefits from full mortgage interest deduction against corporation tax
• Interest-only BTL mortgages — widely available: Unlike the owner-occupied residential mortgage market (where interest-only mortgages are very restricted), interest-only BTL mortgages are routinely available from most BTL lenders. Interest-only means the monthly payment is the interest on the loan only — the capital is not repaid during the mortgage term and must be repaid at the end (typically from the sale of the property). Many BTL investors deliberately choose interest-only to maximise cash flow — the monthly payment is lower than on a repayment mortgage, improving rental yield. The mortgage term for interest-only BTL products is typically 5-35 years. Some lenders offer a mix of interest-only and repayment. Lenders assess whether the landlord has a credible repayment strategy for the capital at the end of the term

Portfolio landlord rules — PRA underwriting standards for 4 or more properties

The Prudential Regulation Authority introduced portfolio landlord underwriting standards in September 2017. These apply additional requirements when a landlord has 4 or more mortgaged BTL properties:

• Portfolio landlord definition: A portfolio landlord is a borrower with 4 or more mortgaged residential properties (whether mortgaged with the same lender or across multiple lenders). The 4-property threshold is based on mortgaged properties — owned outright BTL properties do not count toward the portfolio landlord threshold. Lenders may count properties that are in the process of completion (exchanged but not yet completed) toward the threshold. If the new purchase would be the landlord's 4th mortgaged BTL property, the lender must apply portfolio landlord criteria to the application
• Additional portfolio landlord requirements: Lenders applying portfolio landlord criteria must assess: (1) a full portfolio overview — all mortgaged and unencumbered BTL properties, their values, rental incomes, and outstanding mortgages; (2) an interest coverage ratio assessment across the entire portfolio — not just the property being mortgaged; (3) a business plan or landlord declaration confirming the portfolio's financial position and future strategy; (4) evidence of rental income for all portfolio properties (tenancy agreements; rental statements; SA105 property income supplementary pages from tax returns). The portfolio assessment allows the lender to identify whether a landlord's overall portfolio is financially robust — a highly leveraged portfolio with low rental coverage on existing properties may prevent additional borrowing even if the new property itself meets coverage criteria
• Portfolio landlord — shop around and use a broker: Portfolio landlord criteria vary significantly between lenders. Some lenders (particularly specialists such as Paragon and Foundation Home Loans) are more experienced in assessing complex portfolio landlord applications than high street banks. Paragon, in particular, specialises in portfolio landlord lending and has bespoke assessment processes. Using a specialist BTL mortgage broker (rather than going direct to a lender) is strongly recommended for portfolio landlords — brokers have access to lenders' specific portfolio criteria and can match the application to the most appropriate lender. Brokers also have access to exclusive BTL mortgage products not available directly from lenders
• Refinancing and portfolio management: Portfolio landlords should proactively manage mortgage product expiries. When a fixed-rate BTL product expires, the mortgage reverts to the lender's standard variable rate (SVR) — typically significantly higher than fixed rates. A remortgage to a new fixed rate product (with the same or different lender) reduces the mortgage payment and improves rental coverage. Remortgaging also allows the landlord to release equity where the property has increased in value (accessing the increased equity at the same or similar LTV). Portfolio landlords with properties across multiple lenders face complex remortgage administration — a portfolio review at least 6 months before each fixed rate expiry is recommended

Section 24 and the personal vs limited company BTL mortgage decision

The Section 24 finance cost restriction — limiting higher-rate income tax relief on mortgage interest to the basic rate — is the most significant factor in the personal name vs limited company mortgage decision:

• Section 24 and personal BTL mortgages: Individual landlords borrowing in a personal name (not a company) are subject to the Section 24 finance cost restriction. Higher-rate (40%) and additional-rate (45%) taxpayers can only deduct 20% (basic rate) of their mortgage interest against rental income — effectively paying income tax on an amount that includes the mortgage interest. For a landlord paying 40% income tax on £20,000 of mortgage interest, Section 24 costs an additional £4,000 in tax per year compared with full deduction (40% deduction giving £8,000 relief, vs 20% deduction giving only £4,000 relief). At scale, Section 24 can turn a modestly profitable BTL portfolio into a loss after tax, even before accounting for other expenses
• Limited company SPV BTL mortgages: A limited company (typically a Special Purpose Vehicle — SPV — set up specifically to hold BTL property) is not subject to the Section 24 restriction — it pays corporation tax (currently 25%) and can fully deduct mortgage interest against its rental income before calculating corporation tax. The after-tax cash flow for a higher-rate taxpayer landlord using a company is often significantly better than borrowing personally. However, limited company BTL mortgages carry higher arrangement fees (typically 1%-3% of the loan vs 0%-1% for personal BTL) and slightly higher interest rates. Additionally, extracting profits from the company (dividends; salary) triggers personal tax — a full tax modelling exercise is needed to compare personal vs company BTL
• Consent to let — converting a residential mortgage: Landlords who have a residential mortgage on their home and wish to let it (rather than taking out a BTL mortgage) need 'consent to let' from their existing lender. Consent to let is permission from the residential mortgage lender to let the property — it does not convert the mortgage to a BTL mortgage. Lenders typically grant consent to let for a limited period (6-12 months) at a small rate premium, with a condition that the landlord obtains a BTL mortgage if the let continues. Letting without consent to let is a breach of the mortgage conditions — potentially triggering immediate repayment. Landlords moving away temporarily and wishing to let their home should apply to their lender before letting begins
• Holiday let mortgages: Properties operated as short-term holiday lets (STLs) require specialist holiday let mortgages — not standard BTL products. Most BTL mortgages prohibit lettings of fewer than 6 months or short-stay tourist accommodation. Holiday let lenders (Hodge; Bath Building Society; Ipswich Building Society; Principality; Leeds Building Society) assess the property differently — based on projected seasonal rental income (often calculated as 30 weeks of income per year) rather than a year-round AST rent. Following the abolition of the FHL tax regime from April 2025, the tax advantages of holiday let mortgages have diminished — the remaining advantage is the higher gross income achievable per night in high-demand locations compared with a standard BTL let

Remortgaging BTL properties — triggers, equity release, and product transfers

Remortgaging a BTL property is a routine and important part of portfolio management. Understanding the triggers and options optimises cash flow and portfolio growth:

• Fixed-rate expiry — avoid reverting to SVR: The most common BTL remortgage trigger is the expiry of a fixed-rate period. Standard BTL fixed rates are for 2, 3, or 5 years. At the end of the fixed term, the mortgage reverts to the lender's standard variable rate (SVR) — typically 2%-4% above the fixed rate available to new borrowers. Landlords should begin remortgage planning at least 3-6 months before the fixed rate expiry, allowing time to apply to a new lender or secure a product transfer with the existing lender. Product transfers (switching to a new product with the same lender) are quicker and cheaper than full remortgage but may not offer the best rate in the market
• Equity release — remortgaging to release capital: If a BTL property has increased in value since the original mortgage was taken out, the landlord can remortgage at the same LTV (e.g., 75%) on the new higher value — releasing the equity as cash. This cash can be used to fund deposits on further BTL purchases, renovations, or other purposes. The equity release itself is not taxable (it is a loan, not income). However, the increased mortgage means higher monthly interest payments — which must still pass the rental coverage stress test. The rental income on the property must exceed 125%-145% of the new (larger) mortgage payment at the stress test rate
• Remortgaging to a limited company: Landlords who wish to transition from personal name BTL to a limited company cannot simply 'transfer' the mortgage — the property must be sold to the company (which triggers SDLT and CGT) and the company takes out a new BTL mortgage in its name. The capital gains and SDLT on incorporation may make the transition uneconomic for established portfolios — particularly post-MDR abolition (no multiple dwellings relief on transferring multiple properties to a company). For landlords building new portfolios, acquiring new BTL properties directly into a company from the outset (rather than transitioning an existing personal portfolio) avoids these costs
• Remortgaging under the RRA 2025 — periodic tenancy implications: From 1 May 2026, all new assured tenancies in England are periodic. BTL lenders typically require a minimum tenancy term of 6 months for security — in the new periodic regime, the tenancy can be ended by the tenant on 2 months' notice at any time. Lenders have updated their BTL criteria to reflect the periodic tenancy framework — periodic assured tenancies are now the standard product, and lenders who previously required a 6-month minimum initial fixed term have adapted accordingly. Landlords remortgaging under the new periodic tenancy framework should confirm with their broker that the periodic tenancy structure is acceptable to their lender and that tenant notice provisions do not materially affect the lender's security assessment

Frequently asked questions