Buy-to-let lenders don't lend on your salary — they lend on whether the rent covers the mortgage with a safety margin on top. That's the rental-cover (ICR) test. Enter your figures and see the maximum loan the rent supports.
The mortgage you'd like to take. We test it against the rent to tell you whether it passes the rental-cover (ICR) check, and how much room you have either way. Leave it as a guide — the result updates as you type.
ICR (Interest Coverage Ratio) is how much higher the rent has to be than the mortgage interest. A 125% ICR means the rent must be at least 1.25× the (stressed) mortgage interest; a higher-rate individual taxpayer is usually stress-tested at 145% because of Section 24 mortgage-interest relief restrictions. Limited companies (SPVs) typically use 125%, which is why so many landlords now buy through one.
The notional interest rate the lender tests you at — usually higher than the rate you'll actually pay, to check you can cope if rates rise. Typical 2026 BTL stress rates run from about 5.5% to 8%. Five-year fixes can be stressed at a lower rate (sometimes the pay rate itself); two-year fixes use the higher figure.
An individual landlord taxed at the basic rate. Lenders typically apply a 125% rental-cover ratio — the gentlest of the three, so it usually supports the largest loan.
An individual landlord taxed at the higher rate. Because of Section 24 mortgage-interest relief restrictions, lenders stress these at a tougher 145% — so the same rent supports a smaller loan.
Buying through a limited company (SPV). Mortgage interest is a business cost, so lenders generally use a 125% ratio regardless of your personal tax band — the reason this structure became so popular after 2017.
Annualise the rent. Monthly rent × 12 gives the yearly rent the lender works from.
Apply the stress test. Divide the annual rent by (stress rate × ICR). That's the maximum loan whose stressed interest the rent still covers.
Sense-check against LTV. If you entered a property value, we flag when the loan would breach the usual 75% loan-to-value cap — sometimes LTV, not rent, is your ceiling.
Payam Azadi explains how lenders stress-test the rent against the mortgage, why higher-rate taxpayers face a tougher 145% test, and when buying through a limited company changes the numbers.
Portfolio, HMO, holiday let or limited-company SPV?
Stress tests and ICR thresholds change a lot by lender. We place buy-to-let cases every week and know which lenders flex — let's find the one that lends most against your rent.
This calculator is a guide. The figures shown are illustrative and based on the inputs you provide — they are not a quote, a mortgage offer, financial advice, or tax advice. Buy-to-let stress rates and Interest Coverage Ratios (ICR) vary widely by lender and product (two-year vs five-year fix, personal vs limited company, portfolio vs first-time landlord). HMOs, multi-unit blocks and holiday lets typically use higher ICRs (150%+). Real affordability also depends on your credit history, deposit, landlord experience and the property — and the rent must be supported by an independent valuer's "market rent" assessment, not the figure you hope to achieve.
Most buy-to-let mortgages are not regulated by the Financial Conduct Authority. Niche Advice Limited accepts no responsibility for any decisions made on the basis of this calculator. Niche Advice Limited is authorised and regulated by the Financial Conduct Authority (FCA Reference: 750263). Your home may be repossessed if you do not keep up repayments on your mortgage.
Stress rates, ICR thresholds and lender criteria change frequently, and your individual circumstances may produce different results.
"How to use this calculator" — short video coming soon.