Skip to content
calculatorzone
UK · 2026/27

First-Time Buyer Mortgage Stress Test

Check a first-home mortgage payment, regular home costs, monthly cash buffer, upfront cash and a higher-rate scenario before setting a property budget.

Last reviewed: 6 August 2026Source: MoneyHelper — mortgage affordability calculatorUpdated every: methodology change
First-Time Buyer Mortgage Stress Test · UKProperty & Land

Continue your plan

Useful next calculations

Related to this calculation

Plan the full cost of moving

Carry sale equity through selling, buying, tax, mortgage and removal costs.

Set a deposit and LTV milestone

Turn a property target into a deposit gap and a local-only monthly saving plan.

Rates & sources

A personal cash-buffer illustration using the price, deposit, rate, term, take-home household income, commitments and home costs entered. It is not a mortgage affordability decision or a formal lender stress test.

Mortgage rateentered by you
Stress scenario+2 percentage points
Home costs and bufferentered by you
Lender decisionnot modelled

Source: MoneyHelper — mortgage affordability calculator — check the linked guidance and any live quote before acting.

When to use this calculator

  • Before buying, renting, refinancing, or reviewing a property investment.
  • When you want to compare cash flow, yield, growth, and ownership costs side by side.
  • When you need a fast estimate before speaking to an agent, lender, or adviser.
  • When you are assessing whether a rental property still makes financial sense after a mortgage rate change.
  • When you want to compare the total cost of renting against owning over a five- or ten-year horizon.

A realistic UK planning example

Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.

Property price (£)

£250,000

Deposit (£)

£50,000

Mortgage rate (%)

£200,000

After entering these figures, review mortgage needed, loan-to-value and entered mortgage rate together rather than in isolation — each metric tells a different part of the story. Then rerun the tool with one input adjusted to see which variable has the biggest effect on all three outputs before you settle on a plan.

How to read your results

Mortgage Needed

Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.

Loan-to-Value

Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.

Entered Mortgage Rate

Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.

Method & assumptionsAuthoritative sources

This first-time-buyer stress test combines a repayment-mortgage estimate with the monthly costs a purchase can hide: existing commitments, regular home costs and a monthly cash buffer that you choose. It also shows a two-percentage-point higher-rate scenario using the same loan and term.

The deposit and entered upfront costs are shown together as cash to complete, rather than treating the deposit as the only cash requirement.

This is not a lender affordability assessment or a mortgage offer. It does not calculate Stamp Duty, benefits, credit scoring, property value or lender criteria. Check the formal lender illustration and professional quotes before committing.

Common mistakes

  • !Comparing rent and ownership costs without including taxes, fees, and maintenance.
  • !Using purchase price alone without testing the impact of financing or vacancy assumptions.
  • !Relying on yield or growth in isolation instead of reviewing the full property case.
  • !Forgetting Stamp Duty Land Tax (or its Scottish and Welsh equivalents), which can add thousands to the true cost of purchase.
  • !Using optimistic rental growth figures without also testing a flat or declining rent scenario to check downside resilience.

What to do next

  • Run a second scenario with a higher rate or lower rental yield to check downside resilience.
  • Compare the result with a buy-versus-rent or stamp duty calculator before making an offer.
  • Use the related guides below to understand agent fees, legal costs, and ongoing maintenance budgets.
  • If you are assessing a buy-to-let, check the gross yield against the net yield after mortgage interest, voids, and management fees.
  • Note down the key figures from this scenario to share with your solicitor or mortgage broker so they are working from the same assumptions.

Frequently asked

No. It is a personal budget stress test. Lenders use their own verified income, expenditure, credit and product criteria.

Use arrow keys to navigate items, Enter or Space to expand/collapse.