UK Lease Extension Cost Calculator
Estimate the likely premium and total cost to extend a residential lease in the UK, including valuation and legal fees. This calculator provides an indicative estimate based on commonly used valuation components (capitalised ground rent, marriage value where applicable, and professional fees). It is for guidance only and not a substitute for a formal valuation or legal advice.
- Page updated:
- Jul 14, 2026
- Tool version:
- v1.1.0
Overview
Estimate the likely cost to extend a residential lease in the UK. This tool provides an indicative premium plus professional fees and an allowance for negotiation/contingency.
It is intended for guidance only; you should obtain a formal valuation from a RICS-qualified surveyor and legal advice from a solicitor specialising in leasehold enfranchisement or lease extensions.
Results
Estimated total cost
$21,066.00
Estimated premium
$13,750.00
Capitalised ground rent
$5,000.00
Professional fees
$2,300.00
How to read the result
- What it means
- The displayed value is an estimate based on your inputs. It represents the calculated scenario under current assumptions, not a guaranteed amount.
- Next step
- Use the result as a starting point. Adjust parameters to compare scenarios and validate with a professional when needed.
- Calculation limits
- The model uses simplified formulas and cannot account for all variables in your specific case (local regulations, personal conditions, temporal changes).
Methodology
Methodology summary (indicative):
- Capitalised ground rent: annual ground rent capitalised using an assumed yield (default 5% / 0.05). This models the value of continuing ground rent to the freeholder.
- Marriage value and premium: where remaining lease length is below 80 years, marriage value typically becomes payable under English law. We approximate the marriage value as 50% of the uplift in value due to granting a new long lease, prorated by the shortfall to 80 years. The premium is then calculated as marriage value less the capitalised ground rent (floored at zero).
- Professional fees: typical solicitor and valuer fees are added to the premium.
- Contingency: a percentage buffer applied to premium+fees to allow for negotiation, rounding or other transaction costs.
Notes and caveats: This is a simplified, illustrative model for planning purposes only. Actual statutory or negotiated premiums can differ substantially depending on precise lease terms, local market conditions, yield assumptions, and detailed valuation methods set out in RICS guidance and the Leasehold Reform, Housing and Urban Development Act. Always instruct a chartered surveyor (RICS) and leasehold solicitor for a formal calculation.
Glossary+−
- Marriage value
The additional value created when the freehold and leasehold interests are brought together (typically payable when a lease has fewer than 80 years remaining).
- Capitalised ground rent
The current annual ground rent converted to a capital value using a yield (capitalisation) rate.
- Premium
The lump-sum payment payable to the freeholder to grant an extended lease or surrender and regrant. Calculations vary by statute and valuation method.
- RICS
Royal Institution of Chartered Surveyors — the professional body setting valuation and surveying standards used in the UK.
Key takeaways
This tool provides an indicative estimate of lease extension cost components: capitalised ground rent, premium (where applicable), professional fees and a contingency buffer.
For formal negotiations or statutory claims obtain a RICS-qualified valuation and legal advice.
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Worked examples
Example: London flat — lease extension estimate
70-year lease remaining, flat market value £350,000, annual ground rent £250. Solicitor fees £1,500, valuer fees £800, contingency 10%.
Interpretation
Indicator output shows capitalised ground rent (annual rent / yield), an estimated premium (marriage value less capitalised ground rent where applicable), added professional fees and contingency. Use this to plan likely costs; obtain a formal valuation for a legally binding figure.
Frequently asked questions
How does the calculation work?
This calculator uses an indicative model combining capitalised ground rent, a simplified estimate of marriage value where the lease is under 80 years, professional fees, and a contingency buffer. It is not a replacement for a formal statutory valuation or legal advice.
When does marriage value apply?
Under UK leasehold enfranchisement rules marriage value generally becomes payable where the lease has fewer than 80 years remaining. See the RICS guidance and statutory rules for detailed treatment.
Is this a legally binding premium?
No. This is an indicative estimate. A solicitor and RICS-qualified surveyor must prepare the formal valuation and statutory claim.
Sources & references
- UK Government - Leasehold reform and enfranchisement guidance: https://www.gov.uk/leasehold-property
- RICS Guidance Note: Service charges in commercial property, valuation guidance and leasehold matters (relevant extracts on premiums and valuation methods): https://www.rics.org
- Leasehold Reform, Housing and Urban Development Act 1993 (statutory framework for lease extension/enfranchisement): https://www.legislation.gov.uk/ukpga/1993/28/contents
Quality & oversight
- Author
- Ugo Candido, MBA
- Maintained by
- Ugo Candido, MBA
- Page updated
- Jul 14, 2026
- Tool version
- v1.1.0