Buy to Let Mortgage UK 2026 — Complete Landlord Guide

How buy to let mortgages differ from residential mortgages

BTL mortgages have distinct features that every landlord should understand:

• Assessment basis: Primarily assessed on rental income (ICR test) rather than personal income — though most lenders also require minimum personal income of £25,000
• Deposit requirement: Typically 20–25% minimum deposit (75–80% LTV) — some lenders require 30%+ for HMOs or new build properties
• Interest rates: BTL rates are typically 0.5–1.5% higher than equivalent residential rates — reflecting higher perceived lending risk
• Repayment structure: Most BTL mortgages are interest-only — the capital is repaid on sale of the property. Capital repayment BTL mortgages are available but less common
• Permitted use: The mortgage terms define permitted letting arrangements — most prohibit short-term letting (Airbnb) without specific lender consent. Breaching permitted use terms can result in the lender calling in the loan

Interest coverage ratio (ICR) — how lenders assess your property

The ICR test is the key underwriting tool for BTL mortgages:

• Basic rate taxpayers: Rent must typically be at least 125% of the monthly mortgage interest payment — calculated at a stressed rate (often 5.5–6%, regardless of the actual mortgage rate)
• Higher rate taxpayers: Most lenders apply an ICR of 140–145% — reflecting the lower after-tax rental profit available to service the mortgage
• Limited company borrowers: Many lenders apply a lower ICR (typically 125%) for limited company borrowers — because company profits are taxed after mortgage interest, avoiding the Section 24 personal tax restriction
• HMOs: Some lenders apply different (often more generous) ICR tests for HMOs — reflecting higher rental yields — but require specialist HMO mortgage products
• Top-slicing: some lenders allow personal income to supplement rental income to meet the ICR test — but this is less widely available in 2026 than in previous years

Limited company BTL — tax and mortgage considerations

Limited company BTL has grown significantly since the Section 24 mortgage interest relief restriction was introduced for personally held properties:

• In a limited company, mortgage interest is fully deductible against corporation tax — no Section 24 restriction applies (unlike personally held properties, where individual landlords can only claim basic rate relief on mortgage interest)
• Corporation tax (2026): 19% for profits under £50,000, 25% for profits over £250,000 — typically lower than higher rate income tax on rental profits for many landlords
• Personal income is extracted as salary (NIC implications) or dividends — often at a lower effective rate than personal income tax on rental profits
• Downside — mortgage pricing: Limited company BTL mortgages are typically priced 0.2–0.5% higher than personal BTL mortgages
• Downside — portfolio transfer cost: Transferring existing personally held properties into a company triggers SDLT and CGT — making the switch expensive for established landlords. Most advisers recommend limited company only for new purchases
• Seek specialist tax and mortgage advice before incorporating — the benefit varies significantly by individual circumstances

Product transfer vs remortgage at renewal

When your fixed rate ends, you have two main options:

• Product transfer (same lender): Switch to a new rate with the same lender — no full underwriting, no new valuation, faster and cheaper. The lender typically does not re-run the full ICR test on a product transfer
• Remortgage (new lender): Move to a new lender for a better rate — full underwriting, new valuation, legal fees (though some lenders offer free legals). The new lender applies their ICR test — some properties that pass a product transfer may fail a new lender's more conservative test
• In 2026, many landlords are product-transferring rather than remortgaging — avoiding new ICR tests they might fail at today's higher stress rates
• Early repayment charges (ERCs): check your current fixed rate's ERCs before considering an early remortgage — they can be significant (1–5% of the outstanding balance)
• Plan 3–6 months before your rate expires: speak to a specialist BTL mortgage broker who can assess whether a product transfer or remortgage is optimal for your specific property and circumstances

Renters' Rights Act 2025 — impact on BTL mortgage lending

The abolition of Section 21 has changed the risk calculation for some BTL lenders:

• Some lenders have updated their criteria to require evidence of Section 8 documentation readiness — landlords who cannot demonstrate correct prescribed document compliance face tighter conditions
• Lenders are increasingly factoring possession timeframes into lending risk — the Section 8 route is slower than the old Section 21 accelerated procedure, increasing potential arrears exposure
• Short-term let mortgages: letting on Airbnb without a specific short-term let mortgage product is a breach of most BTL mortgage terms — specialist products are available from a limited range of lenders
• Student HMO mortgages: Ground 4A (the student HMO possession ground) has been noted favourably by some specialist lenders as reducing possession risk in the student market

Frequently asked questions