How Rising Interest Rates Affect Mortgage Affordability in the UK

By WIS Team

March 27, 2026

3 minutes read

TLDR

When interest rates increase, mortgage affordability may change. Lenders assess whether borrowers can afford repayments using affordability stress tests that assume higher interest rates. As rates rise, the maximum loan amount borrowers may qualify for can decrease, even if their income remains the same.

Key Point	Summary
Mortgage affordability	Lenders assess whether repayments are manageable
Impact of rising rates	Higher rates may reduce borrowing capacity
Stress testing	Lenders assess affordability using higher assumed rates
Improving affordability	Deposits, lower debts, and longer terms may help

How Mortgage Affordability Is Calculated

Mortgage affordability refers to how lenders determine whether a borrower can comfortably repay a mortgage.

Lenders usually consider several factors:

Income
Existing financial commitments
Credit profile
Deposit size
Interest rate assumptions

When interest rates increase, lenders often apply higher affordability stress tests, which may reduce the loan amount a borrower qualifies for.

Example of Affordability Impact:

Scenario	Lower Rate Environment	Higher Rate Environment
Household income	£60,000	£60,000
Interest rate assumption	3%	5%
Estimated borrowing capacity	Higher	Potentially lower

Figures will vary depending on lender criteria.

Why Lenders Use Affordability Stress Tests

Mortgage lenders assess affordability at higher assumed interest rates to ensure borrowers could still manage repayments if rates increase during the mortgage term. This approach helps reduce the risk of borrowers experiencing financial difficulty if market conditions change.

Factors That May Improve Mortgage Affordability

Strategy	Potential Benefit
Increasing deposit	Reduces loan amount
Reducing existing debts	Improves affordability calculations
Longer mortgage term	May reduce monthly repayments
Strong credit history	May improve lending options

Real Life Example

A first-time buyer with a household income of £55,000 initially expected to borrow around £275,000 based on earlier affordability estimates. However, as mortgage interest rates increased, the lender’s affordability calculations changed slightly, meaning the maximum borrowing available was lower. After adjusting their property search and increasing their deposit, the buyer remained within the lender’s criteria and continued with their mortgage application.

FAQs

1. Do higher interest rates reduce how much I can borrow?

Higher interest rates can reduce borrowing capacity because lenders stress-test repayments.

2. Do all lenders calculate affordability the same way?

No, each lender applies different affordability criteria.

3. Can a larger deposit improve affordability?

Yes, it reduces the loan amount required.

4. Can a longer mortgage term help affordability?

In some cases, it may reduce monthly repayments.

5. Should I wait for rates to fall before buying?

This depends on individual circumstances and market conditions.

FCA Disclaimer

Your home may be repossessed if you do not keep up repayments on your mortgage.
Lending is subject to status, affordability assessment and lender criteria.
This article is for general information only and does not constitute personalised financial advice.