Buy-to-Let Stress Test Calculator
Find Out If Your Deal Passes Before You Apply.
Check whether your rental income covers lender ICR requirements at stressed interest rates. Know your numbers before you speak to a broker. Instant results, no signup needed.
What is a buy-to-let stress test?
A buy-to-let stress test is the calculation a lender uses to check that the rent will cover the mortgage. The lender applies an interest coverage ratio (ICR) and a notional stressed interest rate to your expected rent. If the rent still covers the mortgage at that stressed rate, the application passes.
What You'll Calculate
Minimum Rent Required
The lowest monthly rent that passes the lender's stress test for your loan size. If your rent is below this, the deal fails.
Your ICR
Your deal's actual Interest Coverage Ratio at the stress rate. Lenders require 125% (limited company) or 145% (personal name, higher-rate taxpayer).
Pass / Fail
An instant verdict at both ICR thresholds so you can see exactly where your deal sits, and what it would take to pass.
Maximum Loan Amount
The maximum you can borrow at the stress rate given your actual rental income. Critical for knowing your deposit gap before you offer.
What's Included
Both ICR thresholds calculated simultaneously: 125% (limited company) and 145% (personal name)
Minimum rent required and maximum loan amount at the standard 5.5% stress rate (as of 2026)
Instant pass/fail verdict based on your tax status and loan size
How It WorkS
Property Value
Enter your purchase price or estimated property value.
Expected Monthly Rent
Input the monthly rental income you expect to achieve for the property.
Select Your ICR Threshold
Choose 125% if buying through a limited company or as a basic-rate taxpayer. Choose 145% if buying in personal name as a higher-rate taxpayer.
Review Your Result
Instant pass/fail verdict, your actual ICR, minimum rent required, and maximum loan amount at the stress rate.
Why It Matters
Your buy-to-let mortgage rate might be 4.5%. But your lender won't assess affordability at 4.5%. They'll assess it at 5.5%, or your product rate plus 2%, whichever is higher.
This stress-tested rate is how lenders check whether you could still cover mortgage payments if interest rates rose significantly. If your rental income doesn't clear the bar at the stress rate, you won't get the mortgage, regardless of your actual rate.
The Interest Coverage Ratio (ICR) is the multiple by which your rent must exceed the stress-tested interest payment. The formula lenders use: (Loan amount x stress rate / 12) x ICR threshold = minimum monthly rent required. On a £150,000 loan at 5.5% with 125% ICR, the minimum monthly rent is £859. At 145% ICR, that rises to £997 per month.
125% ICR applies to limited company purchases and basic-rate taxpayers. Your monthly rent must be at least 1.25x the monthly interest payment calculated at the stress rate.
145% ICR applies to higher-rate taxpayers buying in personal name. Your rent must cover 1.45x the same payment. That is a meaningfully higher bar.
This is one of the main reasons serious property investors buy through limited companies (SPVs). The lower ICR threshold increases maximum borrowing for the same rental income, and combined with Section 24 tax relief, the numbers often stack better too.
The stress test does not just protect lenders. It protects you. A deal that fails at 5.5% may not be investable if rates rise. Use this as a deal filter, not just a mortgage check.
Failing the stress test doesn't automatically kill a deal. You have four levers:
Increase your deposit. A larger deposit reduces the loan, which reduces the minimum rent needed to pass. Run the calculator again with a higher LTV.
Find a higher-yielding property. The same loan amount on a property with stronger rent is a different deal entirely.
Buy through a limited company. If you're a higher-rate taxpayer buying in personal name, switching to a limited company drops your ICR requirement from 145% to 125%, which is often the difference between pass and fail on the same deal.
Use a specialist lender. Some lenders allow top-slicing, assessing affordability using other income alongside rent. A broker who works with investors can identify these options.
ICR (Interest Coverage Ratio)
Capital remaining after refinancing. Negative = successful recycling. Positive shows trapped capital.
Stress Test Rate
The interest rate lenders use to calculate affordability. Currently 5.5% or product rate + 2%, whichever is higher.
Minimum Rent Required
The lowest monthly rent that would pass the stress test for your loan amount. Your actual rent must be at or above this figure.
Maximum Loan Amount
Maximum borrowing allowed at the stress rate given your actual rental income and ICR threshold.
Common Questions
What interest rate do lenders use for the buy-to-let stress test?
What is the difference between 125% and 145% ICR?
Do all lenders use the same stress test rate?
How do you work out a buy-to-let stress test?
How do you pass the mortgage stress test?
What if my rental income just misses the stress test?
Can I use a limited company to get a lower ICR threshold?
Does the stress test apply to remortgages too?
What ICR do buy-to-let lenders require?
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