Leasehold Extension Cost: A UK Guide for 2026
What a leasehold extension really costs in 2026: premium, marriage value, professional fees, SDLT and the tax angles every UK flat owner should plan for.
Quick answer
A leasehold extension cost in 2026 is the premium paid to the freeholder plus professional fees on both sides. There is no fixed price: the premium rises sharply once your lease falls below 80 years because marriage value is added. Get a RICS valuation before you commit, and act early to keep costs down.
What you are actually paying for
When people ask about a "lease extension cost" they often expect a single number. There is not one. The total breaks down into clear components, and understanding each is the only reliable way to budget.
The largest item is usually the premium -- the lump sum you pay the freeholder to grant the longer lease. The rest is professional fees: your own surveyor and solicitor, and, under the statutory route, the freeholder's reasonable costs too.
| Cost component | Who you pay | Typical driver |
|---|---|---|
| Premium | Freeholder | Lease length, ground rent, flat value |
| Your valuation | RICS surveyor | Complexity of the case |
| Your legal fees | Your solicitor | Formal vs informal route |
| Freeholder's costs | Freeholder | Their reasonable surveyor and legal fees |
| SDLT (if any) | HMRC | Premium above the threshold |
How the premium is calculated
The statutory premium reflects three main elements that a valuer brings together. None of these is a figure we can quote for you, because each is specific to your flat, but the mechanism is consistent.
Loss of ground rent
The freeholder loses the future ground rent income that the existing lease would have produced. A valuer capitalises that future income stream into a present-day sum using a capitalisation rate. The higher your ground rent, the larger this element.
The reversion
The freeholder also owns the right to get the flat back at the end of the lease -- the reversion. Extending the lease pushes that date much further into the future, reducing the present value of the reversion to the freeholder. A deferment rate is used to discount it back to today's money.
Marriage value
This is the element that makes the 80-year threshold matter so much. Marriage value is the extra worth created by combining the leaseholder's and freeholder's interests through the extension. Where the unexpired term is below 80 years, the freeholder is entitled to half of that uplift, and it is added to the premium.
Why the 80-year rule dominates the decision
Because marriage value can be the difference between a modest premium and a large one, timing is the most powerful lever a leaseholder has. A lease at 82 years is in a very different position from one at 78 years, even though the difference is only four years.
The practical takeaway is simple: if your lease is anywhere near 80 years, get a valuation now rather than waiting. Each year that passes increases the premium, and once you drop below 80 the increase steepens.
Professional fees and the freeholder's costs
You will normally need a RICS surveyor to value the premium and a solicitor to handle the legal work. Under the statutory route you are also responsible for the freeholder's reasonable professional costs. In effect you are paying for two surveyors and two solicitors.
These costs must be reasonable and can be challenged at the First-tier Tribunal if they are excessive. Getting your own independent valuation early gives you a benchmark to judge whether the freeholder's premium and costs are fair before you commit.
Stamp Duty Land Tax on a lease extension
A lease extension is treated as acquiring a chargeable interest, so Stamp Duty Land Tax can apply where the premium exceeds the relevant threshold. Many extensions fall below the threshold and pay nothing, but a high-value premium can trigger a charge.
We are not going to quote SDLT bands here, because the thresholds and rates change and differ across the UK -- Scotland uses Land and Buildings Transaction Tax and Wales uses Land Transaction Tax instead. Check the current position on gov.uk and model your figure before you complete.
Stamp Duty Calculator
Calculate Stamp Duty Land Tax (SDLT) for your property purchase in England.
Open Stamp Duty calculatorThe tax angle when you sell
For most owner-occupiers the premium is not deductible against income. However, it is usually allowable as enhancement expenditure when you later sell the flat, which reduces any chargeable gain.
If the flat is your main home, Private Residence Relief usually means no Capital Gains Tax arises at all. If it is a let property, CGT may be due. For 2026/27 the Annual Exempt Amount is GBP 3,000, and residential gains are taxed at 18% within the basic-rate band and 24% for higher-rate taxpayers. Keep every invoice and the valuation so you can claim the relief, and model the position with the calculator below.
Capital Gains Tax Calculator
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Open Capital Gains Tax calculatorHow a short lease hits your mortgage and sale
A short lease is not just a future cost -- it affects your flat's value and saleability today. Many lenders will not lend on leases with fewer than around 70 years remaining, and some want considerably more. A flat that fewer buyers can mortgage is a flat that sells for less.
Extending the lease widens your pool of buyers and generally lifts the value. If you intend to sell or remortgage, extending first is often the better sequence. Use the mortgage calculator to see how lease length feeds into what a buyer can borrow.
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Calculate monthly mortgage payments, total interest, and full repayment cost.
Open Mortgage calculatorFormal versus informal: choosing your route
The statutory route follows legislation: you serve a formal notice, the premium is valued on a defined basis, and any dispute goes to the First-tier Tribunal. It gives you legal protection on price and terms but involves the freeholder's costs and a defined timetable.
The informal route is a private negotiation. It can be quicker and cheaper on fees, but the freeholder can decline or set their own price and conditions, and you have no statutory backstop. Many leaseholders open informally and switch to the formal route if the terms offered are poor.
The right choice depends on how reasonable your freeholder is, how strong your negotiating position is, and how close your lease is to 80 years. When in doubt, the statutory route is the safer default because it caps the freeholder's behaviour.
A practical order of events
- Check your remaining lease term and ground rent on the lease document.
- If you are near 80 years, act now rather than later.
- Instruct a RICS valuer to estimate the premium.
- Decide between the informal and statutory routes.
- Instruct a solicitor experienced in enfranchisement.
- Budget for the premium, both sides' fees and any SDLT.
- Keep all paperwork for a future CGT calculation.
Should you buy the freehold instead?
In a block of flats, leaseholders can sometimes club together to buy the freehold collectively. That removes ground rent and gives control over management and service charges, though it requires enough flats to participate and a shared cost. For a house, buying the freehold outright is often the cleaner solution.
Whether extending or buying the freehold is better depends on the number of participating flats, the cost split and your long-term plans. Take RICS and legal advice and compare the total cost of each path before deciding.
The bottom line
There is no single "lease extension cost" -- there is a premium driven by your lease length, ground rent and flat value, plus fees on both sides, and possibly SDLT. The one rule that holds for nearly everyone is to act before the 80-year threshold, because marriage value is the largest avoidable expense. Get a RICS valuation, model the tax and borrowing impact with the calculators above, and take legal advice before you serve notice.
Frequently asked questions
How much does a leasehold extension cost in 2026?
There is no fixed price. The total is the premium paid to the freeholder plus professional fees. The premium depends on the unexpired lease term, the ground rent, the flat's value and the capitalisation and deferment rates used by valuers. Flats with under 80 years remaining cost considerably more because marriage value is added. On top of the premium, budget for your own surveyor and solicitor and the freeholder's reasonable costs. Always get a RICS valuation before committing.
Why is 80 years the critical threshold?
Once an unexpired lease drops below 80 years, the statutory premium includes marriage value -- the increase in the flat's value created by extending the lease, of which the freeholder is entitled to half. This can add thousands of pounds. Extending before you reach 80 years avoids marriage value entirely, so acting early is usually the single biggest cost saving available to a leaseholder.
Do I pay Stamp Duty Land Tax on a lease extension?
SDLT can apply if the premium you pay exceeds the relevant threshold, since a lease extension is treated as acquiring a chargeable interest. Many extensions fall below the threshold and pay nothing, but high-value central London premiums can trigger a charge. The bands and thresholds change over time, so check the current rates on gov.uk and model the figure with our SDLT calculator before you complete.
Can the freeholder refuse a lease extension?
If you qualify under the statutory route -- broadly, owning the flat as a long leaseholder -- the freeholder cannot refuse a formal claim, only negotiate the premium and terms. A voluntary, informal extension is different: the freeholder can decline or set their own price and conditions. The statutory route gives you legal protection and a defined process, including the right to refer disputes to the First-tier Tribunal.
How long does a lease extension take?
A statutory extension commonly takes six to twelve months from serving notice to completion, depending on how quickly valuation is agreed and whether the case goes to tribunal. Informal negotiations can be faster but offer fewer protections. Start early: the clock matters because the closer your lease gets to 80 years, the more the premium rises, and a falling term can also affect your ability to sell or remortgage.
Will a short lease affect my mortgage?
Yes. Many lenders will not lend on leases with fewer than around 70 years remaining, and some want a longer term than that, which shrinks your pool of buyers and can depress the sale price. A longer lease generally makes the flat more mortgageable and more valuable. If you plan to sell or remortgage, extending first can widen your buyer pool. Model the borrowing impact with our mortgage calculator.
Is the lease extension premium tax deductible?
For most owner-occupiers it is not deductible against income, but the premium and associated costs are typically allowable as enhancement expenditure when you later sell, reducing any Capital Gains Tax. Your main home is usually covered by Private Residence Relief, so CGT may not arise at all. For a let property the position differs. Keep every invoice and the valuation, and check the treatment with a tax adviser for your circumstances.
What is the difference between the formal and informal routes?
The formal (statutory) route follows legislation: you serve notice, the premium is valued on a defined basis, and disputes go to the First-tier Tribunal. The informal route is a private negotiation with the freeholder, which can be quicker and cheaper in fees but carries no statutory protection on price or terms. Many leaseholders begin informally and switch to the formal route if negotiations stall or the offered terms are poor.
Do I pay the freeholder's legal and valuation fees?
Under the statutory route you are generally responsible for the freeholder's reasonable professional costs as well as your own. These must be reasonable and can be challenged if excessive. Budget for two surveyors and two solicitors in effect. Getting your own RICS valuation early helps you judge whether the freeholder's premium and costs are fair before you commit to the process.
Should I buy the freehold instead?
For a block of flats, leaseholders can sometimes club together to buy the freehold collectively, which removes ground rent and gives control over management. For a house, buying the freehold (enfranchisement) is often straightforward. Whether extending or enfranchising is better depends on the number of participating flats, the cost split and your long-term plans. Take RICS and legal advice to compare the total cost of each option.
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