AssetCalcs.

Buy-to-Let Mortgage Calculators

Model your property's rental cover ratio and see if you qualify for a Buy-to-Let mortgage.

📍Market Context:

Executive Summary

What is a Buy-to-Let Mortgage? A Buy-to-Let (BTL) mortgage is a UK loan designed for purchasing property to rent to tenants. Lenders underwrite these loans based on the property's projected rental income rather than the borrower's personal salary.

  • ICR Stress Test: Lenders require the rental income to cover 125% (for basic-rate taxpayers/SPVs) or 145% (for higher-rate taxpayers) of the mortgage interest.
  • Stress Rate: Lenders typically model payments at a stressed interest rate of 5.5% or higher to ensure affordability.
  • Deposit: A minimum deposit of 25% (75% LTV) is standard.

Property & Loan Details

£
£
£
5.50%

UK lenders typically stress test at 5.5% or pay rate + 2%.

Loan to Value (LTV)

75%

Interest Coverage Ratio

1.39x
PASSES STRESS TEST (≥1.25x)
Monthly Rent£1,200
Stressed Mortgage Payment-£859
Stressed Monthly Cashflow£341

Browse Rates by Location

Targeted BTL Calculators

Interest OnlyLimited Company (SPV)ScotlandNationwideHalifaxHSBCNatWestSantander

BTL Calculators by UK County

Greater LondonGreater ManchesterWest MidlandsWest YorkshireMerseysideSouth YorkshireHampshireKentEssexNottinghamshire

The Ultimate Guide to Buy-to-Let Mortgage Underwriting

Securing a buy-to-let mortgage in the UK is fundamentally different from a residential mortgage. Instead of evaluating your personal salary, lenders focus primarily on the property's rental income potential. Our btl mortgage calculator is designed specifically to help landlords stress-test deals using the same underwriting criteria high-street banks use.

Understanding BTL Stress Testing and ICR

UK BTL underwriting is governed by the Interest Coverage Ratio (ICR). Lenders want to ensure that the rental income covers the mortgage payments with a substantial safety buffer to account for taxes, void periods, and maintenance. The stress test consists of two main parameters:

  • Stress Interest Rate: The hypothetical rate lenders use to model payments. By default, lenders stress BTL loans at 5.50% or the pay rate plus 2.0%, whichever is higher.
  • Interest Coverage Ratio (ICR): Lenders require a minimum ICR of 125% for basic-rate taxpayers or Limited Company SPVs. For higher-rate taxpayers, the ICR requirement increases to 145% to offset tax changes.

Limited Company SPV vs. Personal Name Ownership

Following Section 24 tax changes in the UK (which phased out mortgage interest tax relief for personal landlords), many property investors now purchase BTL assets through a Special Purpose Vehicle (SPV) Limited Company.

Because Limited Companies pay corporation tax rather than personal income tax, they qualify for the lower 125% ICR stress test, allowing you to borrow more capital against the same rental income. Use our calculator above to switch between tax status options to see how your borrowing capacity is affected.

Educational Guide

UK Buy-to-Let Mortgages & Interest Coverage Ratio (ICR) Stress Testing

Understand UK landlord underwriting rules. Read our complete guide on basic vs higher rate taxpayer stress limits, Limited Company SPV setups, and bridging loan exits.

Read Full Guide →

Frequently Asked Questions

What is a Buy-to-Let (BTL) mortgage?

A Buy-to-Let mortgage is a specialized loan designed for purchasing a property you intend to rent out to tenants. Unlike residential mortgages which are based on your personal income, BTL lenders assess your eligibility primarily on the property's projected rental income.

What is the minimum deposit for a Buy-to-Let mortgage in the UK?

The standard minimum deposit for a BTL mortgage in the UK is 25% of the property's value (a 75% Loan-to-Value). However, some lenders may accept a 20% deposit if you have an excellent credit profile and the property has a very strong rental yield.

How do lenders calculate Buy-to-Let affordability (ICR)?

Lenders use an Interest Coverage Ratio (ICR) to determine how much you can borrow. They typically require the gross monthly rental income to be at least 125% to 145% of the monthly mortgage interest payment. This is often calculated using a "stress-test" interest rate (e.g., 5.5% or 2% above the pay rate) to ensure you can afford payments if rates rise.

Can I live in my own Buy-to-Let property?

No. It is a strict breach of your mortgage terms to live in a property financed by a standard Buy-to-Let mortgage. If you intend to live in the property, you must apply for a residential mortgage instead.