There is no single stress-testing rate
That is the key point to keep in mind. The planner shows the payment effect of a rate rise, but lenders can still use different approaches when they assess affordability.
Stress Test Calculator
Check how a higher mortgage rate would change the payment
Test rate-rise scenarios on the same mortgage, compare the result with your own budget and income context, and see the pressure early rather than after a deal ends.
Rate-rise scenariosRepayment and interest-only modesBudget and income context
Rate Basis
There is no single universal lender stress-testing rate
Five-Year Fixes
No interest-rate stress test is required where the initial fixed period is at least five years
Review Timing
Start talking to your lender around six months before your deal finishes
Planning Tool
Test your own scenario before the payment becomes a problem
Enter the mortgage, choose a rate rise to test, and then compare the result with your own budget and income if you want a household view as well as a payment view.
Rate-Rise Scenario
Enter the mortgage you want to test, then choose the rate rise you want to model. Add income and budget if you want household context alongside the payment change.
Repayment basis
£
%
%
years
£
Optional. Used only to show what the mortgage would cost as a share of gross annual income.
£
Optional. Used only to compare the payment against the monthly limit you choose.
Chosen Scenario
If the rate moved from 4.50% to 6.50%, the monthly payment would move from £1,389.58 to £1,688.02.
Use this as a payment-planning view on the same mortgage. Lender affordability methods can still differ by firm and product.
Current Payment
Repayment Basis
RepaymentMonthly Payment
£1,389.58Annual Cost
£16,675Share of Gross Income
33.3%Optional context only
If Rates Rise by 2.0%
Scenario Rate
6.50%Monthly Payment
£1,688.02Monthly Change
+£298.44Annual Change
+£3,581Share of Gross Income
40.5%Annual mortgage cost / annual gross income
Budget Check Against Your Own Limit
With a monthly housing budget of £1,600.00, the current payment leaves +£210.42 and the chosen scenario leaves -£88.02.
Positive numbers mean room left inside your chosen budget. Negative numbers mean the scenario goes beyond it.
| Rate | Change | Monthly | Monthly Change | Annual Cost | % of Income | Budget Gap |
|---|---|---|---|---|---|---|
| 4.50% | Current rate | £1,389.58 | +£0.00 | £16,675 | 33.3% | +£210.42 |
| 5.50% | +1.0% | £1,535.22 | +£145.64 | £18,423 | 36.8% | +£64.78 |
| 6.50% | +2.0% | £1,688.02 | +£298.44 | £20,256 | 40.5% | -£88.02 |
| 7.50% | +3.0% | £1,847.48 | +£457.90 | £22,170 | 44.3% | -£247.48 |
| 8.50% | +4.0% | £2,013.07 | +£623.49 | £24,157 | 48.3% | -£413.07 |
| 9.50% | +5.0% | £2,184.24 | +£794.66 | £26,211 | 52.4% | -£584.24 |
How to Use the Numbers
The table shows what happens to the same mortgage if rates rise, using either repayment or interest-only maths depending on the basis you choose.
The income and budget columns are personal planning aids. They are intentionally separate from any lender underwriting decision.
If you are coming to the end of a fixed or discounted deal, use the stressed scenarios to decide how early you need to review replacement options rather than waiting for the lender's default rate to arrive.
How To Use It
What this planner is designed to show
Use the result as a planning check, not as a lender decision. These points explain what the planner is showing and where lender judgement still takes over.
Five-year fixes are treated differently in the rule
No interest-rate stress test is required where the initial fixed-rate period is at least five years from the expected start date. That is one reason the same shortcut rule cannot be applied to every mortgage.
Your own budget line matters even when lender rules differ
This planner lets you enter a monthly budget because many people want to know whether a higher payment still fits their real household plan, not just whether a lender might allow it.
Repayment and interest-only maths are shown separately
Those two structures react differently to rate changes, so the tool makes you choose the basis instead of hiding it behind one blended output.
Use Cases
Three practical situations this planner is built for
Most borrowers are not stress testing in the abstract. They are usually trying to answer one of these next-step questions.
Checking the payment before a fixed deal ends
Use the planner to see what the mortgage could look like once the current fixed period finishes, before you start comparing replacement deals.
Comparing repayment and interest-only exposure
Use both payment bases when the structure of the mortgage matters as much as the rate rise itself. The monthly jump can look very different between the two.
Testing the payment against your own household limit
Use the optional budget and income fields if you want to know whether a higher payment still fits the monthly plan you are actually trying to protect.
Worked Example
A simple example using the same maths as the planner
This example uses a £250,000 repayment mortgage over 25 years. It shows the payment movement only, not what a lender will accept.
| Scenario | Rate | Monthly payment | Change vs current |
|---|---|---|---|
| Current rate | 4.50% | £1,389.58 | Current payment |
| Rate rises by 2 points | 6.50% | £1,688.02 | +£298.44 |
| Rate rises by 3 points | 7.50% | £1,847.48 | +£457.90 |
Next Steps
What to do with the result if the stressed payment looks tight
Use the result early, before a deal ends or the payment becomes unmanageable.
If you are still fixed, use the quiet period before the deal ends
Your payments stay the same during the fixed term, but if you do nothing when the deal ends you will usually move onto the lender's SVR.
Start reviewing options around six months before the switch point
You can usually start talking to your lender around six months before your deal finishes, which gives you more time to compare replacement deals.
If you think you will struggle, contact the lender early
If you are worried about making the payments, contact the lender as soon as possible. Waiting usually reduces the number of workable options.
Pair the result with affordability and fees checks
A rate-rise scenario is only one part of the decision. The next step is usually to review the whole monthly budget, buying costs or remortgage options together.
Affordability Planner
Check the wider monthly budget and borrowing context alongside the stress scenario.
Mortgage Calculator
Compare repayment and interest-only maths in more detail if you want a broader payment view.
Remortgage 2026 Guide
Read the action-plan page if your current deal is ending and you need a switching plan.
Mortgage Basics Guide
Use the guide for a cleaner explanation of mortgage types, SVR and lender checks.
Frequently Asked Questions
Does this planner tell me whether a lender will approve the mortgage?
No. This tool is a planning aid. Under FCA rules there is no single prescribed interest-rate stress-test basis for every lender or product, so the planner focuses on payment movement rather than approval labels.
Do all lenders stress test at current rate plus 3%?
No. The rule does not prescribe one universal rate basis. The approach can differ by lender and product, and no interest-rate stress test is required where the initial fixed period is at least five years from the expected start date.
Why does the page ask for my own monthly budget and income?
Those fields are optional context for your own planning. They help you see what the payment would look like against the monthly limit or income figure you personally want to test, instead of assuming every household uses the same comfort line.
What happens if I am on a fixed deal right now?
Your payment stays the same during the fixed term, but if you do nothing when the deal ends you will usually move onto the lender's standard variable rate. That makes the planner useful before the fixed period finishes.
When should I start reviewing my mortgage options?
You can usually start talking to your lender around six months before your deal finishes and should not wait until the lender's default rate is already in place.