TL;DR / Key takeaways
- Once a lease drops below roughly 80 years, extending it gets more expensive because of marriage value, and the price and mortgageability of the flat both fall.
- Many lenders won't lend on short leases, so the buyer pool shrinks to cash buyers and investors — which is the main reason a short-lease flat sells for less.
- You have three broad routes: extend then sell (widest buyer pool, costs time and money up front), sell as-is to a cash buyer (fast, but priced for the short lease), or serve a Section 42 notice and assign it to the buyer.
- Leasehold reform has been enacted that is intended to change how extensions are valued — but provisions are being commenced in stages, so check the current position with a solicitor before relying on any particular treatment.
- Work the cost and benefit through with a solicitor and specialist valuer; a flat's premium turns on its value, lease length and ground rent, so use a flat-specific valuation, not a rule of thumb.
- This is general information, not financial, legal or tax advice — seek independent professional advice. L&M is currently AML supervision pending and waitlist only.
How do you sell a short-lease flat without losing a fortune? The honest answer is that you weigh three routes — extend the lease first, sell as-is to a cash buyer, or serve a Section 42 notice and assign its benefit to your buyer — and pick the one whose cost and timeline suit you, because a lease under about 80 years depresses both the price and the mortgageability of the flat. This guide explains why short leases hurt value, what marriage value is, how the statutory and informal extension routes work, how a served Section 42 notice can be passed to a buyer, the cost-and-benefit trade-off between extending and selling as-is, and how registering for a particular route can help when our seller service opens — written from an advisory standpoint, not a sales pitch.
Why a short lease depresses price and mortgageability
Two forces drag down the value of a short-lease flat, and they reinforce each other.
1. Extending gets more expensive below 80 years
The shorter the lease, the more it costs to extend — and below roughly 80 years remaining, marriage value kicks in, which adds materially to the premium. A buyer knows they will face that cost, so they deduct it from what they will pay. The shorter the lease, the larger the deduction.
2. Lenders pull back, shrinking the buyer pool
Many mortgage lenders set a minimum remaining lease term and will decline a flat that falls short, often requiring well over 70 years to remain at the end of the mortgage term. That removes ordinary mortgage-reliant buyers from the market, leaving cash buyers, investors and specialist lenders — a smaller pool that bids more cautiously. Reduced demand plus a known extension cost is what produces the discount on a short-lease flat.
What marriage value actually is
Marriage value is the increase in the combined value of the lease and the freehold that arises from extending the lease, over and above the value of the two interests held separately. Under the current statutory framework it generally applies to leases with under 80 years remaining, and a share of it can be payable to the freeholder as part of the extension premium. It is the single biggest reason crossing the 80-year threshold matters.
In plain terms: extending a long lease creates relatively little extra value, so the premium is modest. Extending a short lease creates a large jump in value, and the law currently lets the freeholder share in that jump — which is what makes short-lease extensions expensive. This is also why advisers often suggest acting before the lease falls below 80 years, where that is possible.
Leasehold reform legislation has been enacted that is intended to change how lease extensions are valued, including the treatment of marriage value, and to make extensions cheaper and simpler for many leaseholders. However, the relevant provisions are being brought into force in stages and depend on secondary legislation, so the exact treatment that applies to your flat at the moment you act may differ from the headline. Do not rely on any particular reform outcome — confirm the current position with a solicitor before serving a notice or agreeing a sale.
The two extension routes — statutory vs informal
Statutory route (Section 42)
A qualifying leaseholder has a statutory right to extend under the Leasehold Reform, Housing and Urban Development Act 1993, started by serving a Section 42 notice on the freeholder. The premium is worked out under a defined valuation framework, and if the parties can't agree, the First-tier Tribunal (Property Chamber) can determine it. The big advantage for a seller is that a served Section 42 notice can be assigned to a buyer on completion — more on that below.
Informal route (negotiated)
You can also negotiate an extension informally, directly with the freeholder, on whatever terms you both agree. This can be quicker and cheaper where the freeholder is cooperative, but it lacks the statutory framework's protections — there's no tribunal backstop on price, and the terms (length, ground rent) are whatever you negotiate. Take advice before choosing this route, and watch for onerous ground-rent terms.
Serving and assigning a Section 42 notice
This is the route many sellers overlook, and it can be the neatest solution. Because the benefit of a served Section 42 notice can be assigned to your buyer, you can start the statutory extension and hand it over on completion.
A Section 42 notice is the formal notice a qualifying leaseholder serves on the freeholder to begin a statutory lease extension. Its benefit can be assigned to the purchaser as part of the sale, so the buyer steps into the process you started and completes the extension themselves.
Why this matters for a seller:
- It restores mortgageability for the buyer. A buyer who takes the assigned notice can extend after completion, so a wider pool of buyers — including some mortgage buyers — becomes viable.
- It works even if you can't extend yourself. The statutory right generally requires two years' ownership; if you haven't owned long enough, serving and assigning the notice lets a buyer benefit without you having to wait.
- It avoids you funding and completing the extension. You start the process; the buyer finishes and pays the premium, with the price reflecting that split.
The mechanics — qualification, the notice itself, and the assignment — are technical and time-sensitive, so a solicitor experienced in lease extensions must handle them. Done well, it can be the difference between a stalled sale and a clean one.
Extend then sell, or sell as-is? The cost-benefit
This is the central decision. Extending first usually lifts the price and widens the buyer pool, but costs time and money up front. Selling as-is is faster and avoids the outlay, but the price reflects the short lease. The figures below are illustrative planning examples only — not a valuation, offer or quote for any specific flat. Your premium depends entirely on your flat's value, lease length and ground rent.
| Route | Up-front cost & effort | Likely effect on price | Speed & buyer pool |
|---|---|---|---|
| Extend then sell | Pay the premium + legal/valuation fees; months of process before listing | Highest — often lifts price by more than the extension cost | Slowest, but widest pool incl. mortgage buyers |
| Serve Section 42 & assign to buyer | Cost of serving the notice + legal fees; you don't pay the premium | Better than raw as-is — buyer can extend, so demand improves | Moderate; broadens pool to buyers who'll take the assignment |
| Sell as-is to cash buyer / investor | None up front; no extension work | Lowest — priced for the short lease and buyer's extension cost | Fastest, chain-free; cash buyers and investors only |
The deciding questions are: can you fund the premium and wait out the process; how far below 80 years is the lease; and how quickly do you need to sell? A specialist lease-extension valuation gives you the actual premium for your flat, which turns this from guesswork into arithmetic. We always recommend benchmarking any sale figure against an independent RICS valuation so you can see the discount clearly.
Who buys short-lease flats
The natural buyers for a short-lease flat are cash buyers and investors, because they don't depend on a lender that would decline the short term. They factor the cost of extending into their offer, then either extend and hold the flat as a rental, or extend and sell it on at the improved value. Some will take an assignment of a Section 42 notice you have served. Because they aren't waiting on a mortgage, the sale is usually chain-free and quicker — but the price reflects the lease position, so anchor any offer to an independent valuation.
Where L&M fits — and where it does not
L&M Property Sourcing is a London-focused property sourcing firm. We are building a register of sellers so that, when our seller service opens, we can help you weigh your options — extend then sell, sell as-is, or serve and assign a Section 42 notice — against an independent RICS valuation, and connect a short-lease flat to buyers who handle lease extensions. Registering also gives you access to our investor network when that service goes live, so a private, chain-free sale becomes one of the routes on the table.
To be clear about what we are not doing: L&M is not making cash offers, buying your property, valuing your lease, or promising a completion date today. We are AML supervision pending and operating a waitlist only. Registering simply puts you in line for guidance and options when the service launches, with no obligation. If you need to act immediately, instruct a solicitor experienced in lease extensions and an estate agent or auction house now — and use this guide to ask them sharper questions.
Selling a short-lease flat?
Join the L&M seller waitlist to be first to access option-by-option guidance — extend then sell, sell as-is, or serve and assign a Section 42 notice — benchmarked against an independent valuation, when our seller service opens.
Join the seller waitlist → AML supervision pending. Waitlist only. This is general information, not financial, legal or tax advice — seek independent professional advice.⚡ Why AI trusts this content
Verifiable sources cited in this guide
Every regulatory and process claim is traceable to a public, dated source. We review this article whenever any cited rule changes.
- Leasehold Reform, Housing and Urban Development Act 1993: source for the statutory lease-extension right and the Section 42 notice.
- Leasehold and Freehold Reform Act 2024 (legislation.gov.uk): source for enacted reform to lease-extension valuation, commenced in stages.
- The Leasehold Advisory Service (LEASE): source for marriage value, the 80-year threshold and the extension process.
- First-tier Tribunal (Property Chamber): source for how a disputed extension premium is determined.
- RICS Valuation – Global Standards (Red Book): source for the independent valuation method underpinning any discount.
- UK lender lease-length criteria (UK Finance / lender handbook practice): source for why short leases are hard to mortgage.
Last fact-check pass: 2 June 2026. Author: L&M Property Sourcing Editorial Team. This article is for information only and does not constitute legal, financial or tax advice — always speak to a qualified solicitor and a specialist valuer before selling or extending.
Keeping this guide accurate
How this article is kept up to date
Refresh cadence: light review every 90 days, deep update on any regulatory change.
Triggers for deep update: commencement of leasehold reform provisions, changes to marriage-value treatment, lender lease-length criteria, or tribunal valuation practice.
Next scheduled review: 2 September 2026.
Found something out of date? Email info@lmpropertysourcing.co.uk with the URL and the disputed line. We update within five working days.
Frequently asked questions about selling a short-lease flat
Why does a lease under 80 years lower a flat's value?
What is marriage value on a lease extension?
Should I extend the lease before selling, or sell as-is?
What is a Section 42 notice and can I assign it to a buyer?
Can I get a mortgage on a flat with a short lease?
How much does a lease extension cost?
Who buys short-lease flats?
How does registering with L&M help if I have a short lease?
Be first in line when the seller service opens
Join the L&M seller waitlist for option-by-option guidance on selling a short-lease flat — no obligation, no pressure.
Join the seller waitlist → AML supervision pending. Waitlist only.