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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: HMRC / Welsh Revenue / Revenue Scotland

Continue your plan

Useful next calculations

Related to this calculation

Rates & sources

SDLT/LTT/LBTT bands vary between England, Wales, Scotland and Northern Ireland. Use the appropriate calculator.

Source: HMRC / Welsh Revenue / Revenue Scotland — 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, tax, yield or ownership costs.
  • When you need a fast estimate before speaking to an agent, lender or adviser.
  • When you want to see how a rate or price change moves the result.

A realistic UK planning example

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

A realistic UK planning example
InputValue
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. Then rerun the tool with one input adjusted.

How to read your results

Mortgage Needed

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Loan-to-Value

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Entered Mortgage Rate

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

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 financing or vacancy assumptions.
  • !Relying on yield or growth in isolation instead of reviewing the full property case.
  • !Using the wrong national transaction-tax calculator for the purchase location.

What to do next

  • Run a second scenario with a higher rate or lower rental yield.
  • Compare the result with a buy-versus-rent or mortgage calculator before making an offer.
  • Use the matching national transaction-tax calculator for the purchase location.
  • Note the key figures to share with your solicitor or lender.

Frequently asked

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

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