How to Extend a Lease on a Leasehold Flat UK: Costs, Process, and Timeline

If you own — or are buying — a leasehold flat, the length of the remaining lease is one of the most important numbers you need to understand. A short lease does not just affect your ability to sell the property in the future; it can make the flat unmortgageable, dramatically reduce its value, and expose you to an expensive and time-consuming legal process.

This guide explains how lease extension works in the UK, the costs involved, and the changes introduced by the Leasehold and Freehold Reform Act 2024.

Why Lease Length Matters

Every leasehold flat is sold with a finite term — often 99, 125, or 999 years when originally created. Over time, that term counts down. When it reaches critical thresholds, serious problems arise:

Below 85 years: Some mortgage lenders begin to require a minimum remaining lease of 85 years plus the mortgage term (typically 25–30 years). This means properties with 85 years or fewer are already in restricted territory for many buyers
Below 80 years: This is the most dangerous threshold. Once a lease falls below 80 years, marriage value is triggered in lease extension premium calculations. Marriage value is the additional premium the freeholder can demand — representing the uplift in property value that the lease extension provides — and it can add tens of thousands of pounds to the cost of extending
Below 70 years: Most high street mortgage lenders, including Nationwide and Halifax, will not lend on a property with a lease of under 70 years without a formal extension in progress. This severely restricts your buyer pool when you come to sell

The key rule: extend before 80 years, ideally before 85.

The Two Routes to Lease Extension

Route 1: The Statutory (Formal) Route

Under the Leasehold Reform, Housing and Urban Development Act 1993, qualifying tenants have the legal right to extend their lease by 90 years on top of the existing term, with the ground rent reduced to a peppercorn (effectively zero). This is a powerful statutory right.

Qualifying conditions (as of June 2026):

You must have owned the flat for at least two years (registered ownership, not exchange)
The flat must be let on a long lease (originally more than 21 years)
The building must not be owned by a charitable housing trust

The process:

Appoint a specialist leasehold solicitor and a RICS-accredited leasehold valuation surveyor
Instruct your surveyor to value the lease extension premium
Serve a Section 42 Notice — a formal statutory notice on the freeholder, stating the premium you are proposing and the terms of the new lease. The notice triggers a statutory timetable
The freeholder has two months to respond with a Section 45 Counter-Notice, accepting your terms or proposing a different premium
Negotiate — most cases resolve by negotiation between surveyors. If no agreement is reached within six months of the Section 45 Counter-Notice, either party can apply to the First-tier Tribunal (Property Chamber) for a determination
Exchange and complete the lease extension — typically 3–6 months from Section 42 Notice to completion if uncontested

The statutory route gives you legal protection: the freeholder cannot refuse, cannot add unreasonable conditions, and must deal with your surveyor.

Route 2: The Informal (Voluntary) Route

You can approach the freeholder directly at any time, without serving formal statutory notices, and negotiate an extension on whatever terms you can agree.

Advantages of the informal route:

Faster — can complete in 2–3 months if both parties cooperate
Lower legal costs (no formal statutory notices to serve)
No two-year ownership requirement — useful for recent purchasers

Disadvantages:

No legal protection — the freeholder can refuse, delay, or impose unfavourable terms
The freeholder may insist on a higher ground rent (though new leases created after June 2022 cannot contain ground rent under the Leasehold Reform (Ground Rent) Act 2022)
Fewer procedural safeguards

For most leaseholders, the statutory route is preferable unless the freeholder is cooperative and the lease is well above 80 years.

Lease Extension Costs

Cost Item	Typical Range
RICS leasehold valuation surveyor (to advise on premium)	£500–£1,500
Your solicitor's fees (for statutory route)	£1,500–£3,000
Freeholder's surveyor's fees (you pay these too)	£500–£1,500
Freeholder's solicitor's fees (you pay these too)	£1,000–£2,000
Land Registry registration fee	£50–£500 (depending on premium)
Tribunal application fee (if contested)	£200–£400

Note: Under the statutory route, you are required to pay the freeholder's reasonable legal and surveyor costs, in addition to your own. Budget for total transaction costs of £3,000–£7,000 on a typical uncontested extension.

The Lease Extension Premium: Example Estimates by Years Remaining

The premium you pay for the lease extension depends on: the current lease length, the value of the flat, the ground rent, and complex actuarial calculations (deferment rate and relativity). Marriage value (if under 80 years) can dominate the premium.

The table below is illustrative for a flat valued at £350,000 with a £250 per annum ground rent:

Years Remaining	Approx. Premium
90 years	£4,000–£8,000
80 years	£10,000–£18,000
75 years	£18,000–£30,000
70 years	£30,000–£50,000
60 years	£55,000–£90,000+

These figures are indicative only. Always commission a specialist RICS surveyor for an accurate valuation before proceeding.

The Leasehold and Freehold Reform Act 2024: What Changed?

The Leasehold and Freehold Reform Act 2024 received Royal Assent in May 2024. Key provisions that have come into force (or are being phased in) include:

Ban on new leasehold houses (with limited exceptions): new houses can no longer be sold as leasehold
Extended lease terms on extension: from 90 years to 990 years on extension (once commenced — full commencement regulations are still pending for this provision)
Marriage value abolished: the most significant reform for leaseholders with short leases. Once fully in force, marriage value will no longer be payable, substantially reducing premiums for leases below 80 years. Implementation date still pending as of June 2026 — check the latest government guidance
Ground rent reform: new leases are already subject to peppercorn ground rent; the Act strengthens enforcement
Right to manage: qualification thresholds for leaseholders to take over management of their building have been widened

What Is Still Pending

The abolition of marriage value and several other key reforms require secondary legislation (commencement orders) to take effect. As of mid-2026, leaseholders should take specific legal advice on which provisions are live before making decisions based on the 2024 Act.

Briefly: Collective Enfranchisement and Right of First Refusal

Collective enfranchisement allows leaseholders in a building to collectively purchase the freehold. If 50% or more of the qualifying leaseholders in a building agree, they have the statutory right to buy the freehold — giving them control over ground rent, service charges, and future lease terms.

Right of first refusal (under the Landlord and Tenant Act 1987): if your freeholder wants to sell the freehold, they must first offer it to the leaseholders before selling to a third party.

Both are more complex than individual lease extensions and require specialist legal advice.

The Key Mistake: Buying a Short-Lease Flat Without Budgeting for Extension

This is one of the most common and costly errors in UK property buying. A flat with 72 years on the lease may appear to be a bargain — but if the buyer does not budget for the cost and time of a lease extension within two years of purchase, they risk:

Being unable to remortgage when their fixed rate expires
Being unable to sell when they want to move
Facing a significantly higher premium if the lease drops further

Before exchanging on any leasehold flat, ask your solicitor: what is the unexpired lease term, is it above 80 years, and what would a lease extension cost? Factor this into your offer price.