Buy to Let Stress Test Calculator

Lenders stress test BTL mortgages by checking if the rental income covers the mortgage interest at a higher 'stressed' rate (typically 5.5–8.5%). The Interest Coverage Ratio (ICR) required is usually 125% for basic rate taxpayers and 145% for higher rate taxpayers.

The Interest Coverage Ratio (ICR) is annual rental income divided by annual interest-only mortgage payment. PRA rules since 2017: standard ICR of 125%. For higher/additional rate taxpayers (due to Section 24 tax rules): 145% or higher. Most lenders apply 145% as standard.

Most lenders stress test at 5.5–8.5% regardless of the actual mortgage rate. Even if your actual rate is 4.5%, the lender calculates affordability at the stressed rate to ensure you can afford payments if rates rise significantly.

Minimum rent = Loan × Stressed rate × ICR ÷ 12. Example: £187,500 loan, 7.5% stress rate, 145% ICR: minimum rent = £187,500 × 7.5% × 1.45 ÷ 12 = £1,700/month. Use our calculator to find your exact minimum.

Most BTL lenders offer up to 75% LTV, requiring a 25% deposit. Some specialist lenders offer 80% LTV at higher rates. The better rates (and easier stress tests) are typically available at 60–65% LTV.

Section 24 (phased in 2017–2020) restricts mortgage interest tax relief to basic rate only for individual landlords. This reduced BTL profits for higher-rate taxpayers, prompting lenders to tighten ICR requirements to 145% for higher-rate taxpayer landlords.

Limited company BTL mortgages typically use a 125% ICR rather than 145%, as Section 24 doesn't apply to companies (full interest deduction is retained). This is one reason many landlords have moved to limited company structures.

A minimum 6–7% gross rental yield is typically needed to pass stress tests and generate positive cash flow after mortgage costs, management fees, and maintenance. In London and the South East, yields of 3–5% make stress tests challenging.

From 2017, lenders must apply stricter underwriting to 'portfolio landlords' (4+ mortgaged properties). They assess the entire portfolio's affordability, not just the individual property. This can restrict lending even if individual properties pass stress tests.

Options: negotiate higher rent before application (get market evidence), reduce the loan amount by increasing deposit, choose a lower stress rate lender, or consider HMO (House in Multiple Occupation) properties which typically command higher total rents.

Yes — lenders apply the same ICR stress test when you remortgage, even if you've held the property for years. If rental income has fallen or rates/stress rates have risen, you may fail to remortgage at the same LTV and face a 'mortgage prison' scenario.

If your BTL mortgage has a fixed rate that will revert to a higher Standard Variable Rate (SVR), lenders may stress test at the SVR (often 8%+). This catches many BTL landlords off-guard — calculate affordability at your lender's SVR before taking a fixed rate deal.