Sellers' Guide
Selling a Flat While a Lease Extension Is in Progress
You have started a lease extension and now need to sell before it is finished. That happens often, and it can be done. The catch is that the statutory deadlines keep running while you sell. This guide explains what you can pass to a buyer and what you cannot, who pays the premium, and where the timing traps are.
Can You Sell a Flat Mid Lease Extension?
Lease extensions take months. The freeholder has two months just to reply, valuations go back and forth and a tribunal hearing can add half a year. Life does not wait that long. People get a job offer, a divorce, a probate deadline or simply a buyer who turns up before the new lease does.
The good news is that the law expected this. The 1993 Act lets a statutory claim pass to a buyer along with the flat, and conveyancers do it routinely. The bad news is that it has to be done precisely, on the day, with the right paperwork, or the claim is treated as withdrawn and nobody can serve a new one for a year. This guide covers how to carry a claim through a sale, how the premium is usually dealt with and what to do if you are on the informal route, where none of the statutory protections apply.
This guide is general information, not legal advice. It covers England and Wales.
Written and kept up to date by the Sell Flat UK team at LDN Properties Ltd, who have bought flats with lease extensions in progress since 2003. Last reviewed on 14 October 2026.
Which Route You Are On Matters More Than Anything
There are two ways to extend a lease, and they behave completely differently in a sale. Our guide to statutory versus informal lease extensions compares them in full. For selling, the difference comes down to one thing: whether there is a legal claim that can be handed to someone else.
The statutory route
You served a section 42 notice under the Leasehold Reform, Housing and Urban Development Act 1993. That notice created a legal claim with a fixed valuation date, a fixed outcome (90 years added, ground rent reduced to a peppercorn) and a timetable the freeholder has to follow. The claim belongs to the lease, and the Act lets you pass it to whoever buys the lease from you. Since 31 January 2025 there is no longer a two-year ownership condition, so a buyer could also start their own claim the day after completion. Taking over yours is still usually better, for the reasons in the next section.
The informal route
You approached the freeholder directly, or they approached you, and you are negotiating a price and terms without a notice. Nothing here binds the freeholder. There is no valuation date, no timetable and nothing a buyer can take over. If the deal is agreed and ready to complete, it can be completed on the same day as your sale, which is common. If it is still being negotiated, a buyer takes the flat as it is and starts their own discussions, or serves their own notice.
Passing a Statutory Claim to the Buyer
Section 43 of the Act lets the benefit of a section 42 notice be assigned to the person who takes the lease. In practice your solicitor prepares a short deed of assignment that completes at the same moment as the transfer of the flat, and the buyer's solicitor tells the freeholder that the claim now belongs to the buyer. From then on, the buyer deals with the counter-notice, the valuation, the tribunal if it comes to that, and the completion of the new lease.
Why the buyer wants your claim rather than their own
The premium is valued at the date the notice was served, not the date the extension completes. If your lease had 80 years and two months left when you served, the premium is calculated on that basis even if the lease has dropped below 80 years by the time the buyer completes the extension. Below 80 years, marriage value is added and the premium jumps, often by thousands of pounds. Our guide to marriage value explains the cliff. A buyer who takes over your notice keeps your valuation date. A buyer who starts again gets today's.
There is a second reason. Your claim is already some months in. The freeholder has replied, or must reply soon, and the valuations may be close to agreement. A fresh notice puts the buyer back at the start, with another two months before the freeholder has to say anything.
The trap in the timing
The assignment has to happen with the transfer of the lease, not after it. If the flat is transferred and the notice is not assigned at the same time, the Act treats the notice as withdrawn. You then owe the freeholder's costs to that point, and no new notice can be served for the flat for twelve months. The buyer, who thought they were getting a half-finished extension, gets a short lease and a year's wait. Both solicitors have to know this is happening and treat it as part of completion. Our guide to lease extension mistakes covers the other ways a claim gets lost in a sale.
The Deadlines That Keep Running During a Sale
A statutory claim has a set of fixed time limits, and none of them stops because the flat is on the market. Whoever holds the claim on the day, you or the buyer, has to meet them.
- The counter-notice. Your notice names a date by which the freeholder must reply, at least two months after service. Their counter-notice either admits the claim, with their own premium, or disputes it.
- The tribunal window. If the premium or terms are not agreed, an application to the First-tier Tribunal (Property Chamber) can be made from two months after the counter-notice and must be made within six months of it. Miss the six months and the notice is treated as withdrawn.
- Completion of the new lease. Once the terms are agreed or decided, the new lease has to be completed within two months. If it is not, either side has a further two months to ask the court to enforce it. Miss both and the claim lapses. Sales have been lost this way when everyone assumed the agreed deal was safe.
- The twelve-month bar. A notice that is withdrawn, or treated as withdrawn under any of the rules above, cannot be followed by a new one for the flat for twelve months, and the freeholder's reasonable costs up to that point are still payable. The 2024 Act will remove this bar when that part of it starts, but no date has been set.
Before you go to market, ask your solicitor to write down where the claim is and the date of the next deadline. Put it in the sale pack. A buyer's solicitor who sees a tribunal deadline three weeks after the target completion date will plan for it. One who finds out afterwards will blame you.
How the Money Usually Works
The premium has to be paid by someone, and the buyer's price reflects who. There are four common structures. Which one suits you depends on how far the claim has got, how long the lease is and how quickly you need to complete.
You finish the extension first
If the premium is agreed and you can fund it, complete the new lease before you exchange. You sell a long-lease flat at a long-lease price and the buyer's lender has nothing to worry about. This gets the best price but needs the cash up front and enough time: from an agreed figure to a registered new lease is typically four to eight weeks.
Simultaneous completion
Where the terms are agreed, statutory or informal, the new lease can be granted to you and the flat transferred to the buyer in the same moment, with the premium paid out of the sale proceeds. The buyer gets a long lease from day one, their lender is satisfied and you never have to find the premium yourself. It takes coordination between three sets of solicitors, and the freeholder's solicitor has to be ready on the day, so start arranging it as soon as you have a buyer.
The buyer takes over the claim
You assign the notice on completion and the buyer pays the premium when the extension completes, weeks or months later. The sale price is the long-lease value minus the expected premium, minus both sides' professional costs, minus something for the risk and delay the buyer is taking on. This is the usual structure when the premium is not yet agreed, and the normal one for a sale to a cash buyer. It does not work well with a mortgage if the current lease is below the lender's minimum.
A retention
Where the premium is nearly agreed but not quite, the solicitors can hold back an agreed sum from your proceeds to cover it, and release what is left once the figure is settled. It gives the buyer protection against the premium coming in high without you having to take the whole discount up front.
A worked example
Take a flat worth £300,000 with a long lease, where the lease had 79 years left when the notice was served. The premium on a lease of that length is around £19,000, and the professional fees for both sides, which you pay as the leaseholder, typically come to £3,000 to £7,500 including VAT. A buyer taking over the claim would start from about £300,000, deduct the £19,000 premium and roughly £5,000 of fees, and then take a further 2 to 5 percent for the time and risk, landing roughly between £260,000 and £270,000. Had the notice been served two months earlier, with the lease just over 80 years, the premium would have been about £6,000 and the same buyer would be paying close to £280,000. The figures are for illustration only. The Leasehold Advisory Service calculator gives an estimate for your own flat.
What the Buyer's Lender Needs
A mortgage lender lends against the lease that exists on completion day, not the one that is coming. Most lenders want a certain number of years left at completion, commonly 70 or more. Many also want the mortgage term plus 30 to 40 years, and some set an absolute minimum of 80 or 85 years at the outset. Our guide to mortgage lenders and lease length sets out the usual thresholds.
That gives three cases. If your lease is still comfortably above the lender's minimum, the lender will usually lend and treat the extension in progress as a bonus, provided the claim is assigned properly. If the lease is close to or below the minimum, the lender will usually insist that the extension completes on or before the day of completion, which means simultaneous completion or finishing first. If the lease is short and the premium is not yet agreed, most lenders will not proceed at all, and the realistic buyers are cash buyers who can wait for the extension to finish after they own the flat.
The buyer's solicitor has to confirm all of this to the lender before exchange, so make sure your solicitor can produce the notice, the counter-notice and the current state of the negotiations as soon as they are asked.
How Much Does It Affect the Price?
Measured against the value of the flat with a long lease, from what we see:
| Situation | What buyers typically deduct from long-lease value | What buyers usually want |
|---|---|---|
| Extension completed before, or on the day of, completion | Nothing beyond the premium and costs you have already paid | The new lease, or a simultaneous completion arranged and confirmed by the freeholder's solicitor |
| Statutory notice served, premium agreed, claim assigned to the buyer | The premium and both sides' costs, plus about 2 to 5 percent | The notice, the counter-notice, the agreed figure in writing and the deed of assignment ready for completion |
| Statutory notice served, premium not yet agreed | The higher of the two valuations, plus costs, plus about 5 to 10 percent | Both valuations and the next deadline. Most lenders will not proceed if the lease is below their minimum. |
| Informal talks only, or a notice that has lapsed | The flat is priced as a short lease flat: the premium, costs and a further 10 to 20 percent depending on the years left | Nothing can be handed over. Cash buyers price in a fresh claim from today's valuation date. |
These are typical ranges, not a valuation. The further the claim has progressed and the more certain the premium, the less the buyer deducts for risk. Our guide on whether to extend before selling looks at the same question from the other end.
Serve Now or Wait for Reform?
The Leasehold and Freehold Reform Act 2024 promises cheaper extensions, with marriage value abolished and a 990-year term. Those parts are not in force. The government's consultation on the valuation rates that will set the new premiums closes on 21 October 2026, a legal challenge by freeholders is listed for the Court of Appeal in April 2027 and no date has been given for the new rules to start. Our news piece on the valuation rates consultation has the detail.
For a seller, the question is simpler than it looks. If you are selling in the next year, reform will not arrive in time to help your buyer, and a buyer will price the flat on today's law. If your lease is anywhere near 80 years, serving a notice now fixes the valuation date before marriage value bites, and that protection passes to the buyer with the claim. If your lease is long and you are not selling soon, waiting may make sense. Our guide to leasehold reform tracks what has changed and what is still pending.
Your Options
| Option | How it works | Best for |
|---|---|---|
| Finish the extension, then sell through an estate agent | Complete the new lease, then market a long-lease flat at full value | Sellers who can fund the premium and have four to eight weeks after the figure is agreed |
| Sell through an estate agent with simultaneous completion | The new lease and the sale complete together, premium paid from the proceeds | An agreed premium, a buyer with a mortgage and solicitors who have done it before |
| Sell through an estate agent and assign the claim | The buyer takes over the notice and completes the extension after they own the flat | A lease still above the lender's minimum, or a cash buyer |
| Sell at auction | The legal pack includes the notice and the assignment, and bidders price the claim | A short lease with a claim in progress where speed matters and the buyers are investors anyway |
| Sell to a cash buyer | The buyer takes the assignment, pays the premium when it falls due and completes in weeks | A deadline of your own, a lease below lender minimums or a premium still in dispute |
Whichever you choose, the claim must not lapse in the gap. Our guides to selling at auction and selling to a cash buyer compare the faster routes, and our page on short lease flats explains how we handle a notice in progress.
What to Do, and What Not to Do
Do:
- Tell your solicitor and your agent on day one that a claim is running. Both need to plan the sale around its deadlines.
- Get the state of play in writing. Notice date, counter-notice date, both valuations, what has been agreed and the next deadline, all on one page for the buyer's solicitor.
- Keep the claim moving while you market. Respond to the freeholder's valuer, and if the tribunal window is closing, apply. A live claim is worth money; a lapsed one costs it.
- Use a solicitor who has assigned a notice before. Ask directly. It is a routine job for a leasehold specialist and a trap for a generalist.
Do not:
- Do not withdraw the notice to make the sale simpler. It triggers the freeholder's costs and the twelve-month bar, and it hands the buyer a worse valuation date.
- Do not assume an agreed informal deal is safe. Until the new lease is signed, the freeholder can change the price or walk away, and a buyer knows it.
- Do not let completion of the sale happen without the assignment. If the two are not done together, the claim is treated as withdrawn.
Sources and Further Reading
- Leasehold Reform, Housing and Urban Development Act 1993, section 42: the tenant's notice, and the twelve-month bar after withdrawal.
- Section 43: assigning the benefit of the notice with the lease, and deemed withdrawal if the lease is assigned without it.
- Section 48 and section 53: the tribunal window and deemed withdrawal.
- Section 60: the leaseholder's liability for the freeholder's costs.
- Leasehold Advisory Service: free guidance on the statutory process and a lease extension calculator.
- Leasehold and Freehold Reform Act 2024: the lease extension reforms, most of which are not yet in force.
Frequently Asked Questions
Yes. The benefit of the notice can be assigned to your buyer on completion under section 43 of the 1993 Act, so they carry on the claim you started. Your solicitor prepares a deed of assignment that completes at the same moment as the sale, and the buyer's solicitor tells the freeholder. The buyer keeps your valuation date and your place in the timetable. The premium and costs are normally reflected in the price.
The notice is treated as withdrawn. You remain liable for the freeholder's reasonable costs up to that point, and no new notice can be served for the flat for twelve months. The buyer ends up with the original short lease and a year's wait before they can start their own claim. The assignment and the transfer of the flat have to be completed together, so both solicitors need to plan for it.
There is nothing to pass on. An informal extension is a private negotiation with the freeholder, with no notice, no valuation date and nothing that binds them. If the deal is agreed and the paperwork is ready, it can be completed on the same day as your sale, with the premium paid from the proceeds. If it is still being negotiated, the buyer either starts their own talks or serves a statutory notice after completion.
Yes, if they take an assignment of your section 42 notice. The premium is valued as at the date the notice was served. If your lease was over 80 years then and has since dropped below, the buyer still pays a premium calculated without marriage value. That can be worth thousands of pounds, which is the main reason a buyer prefers your notice to serving their own.
The buyer pays it to the freeholder when the extension completes, because by then they own the lease. In return, the sale price is set at the long-lease value minus the expected premium, minus both sides' professional costs, minus a margin for the buyer's time and risk. If the premium is agreed but not yet paid, a simultaneous completion lets you pay it from the sale proceeds and sell a long-lease flat instead.
It depends on the lease that exists on completion day. If the current lease is above the lender's minimum, usually 70 years or more, most lenders will lend and treat the assigned claim as a bonus. If it is near or below the minimum, the lender will normally require the extension to complete on or before completion, which means finishing it first or completing simultaneously. If the lease is short and the premium is still in dispute, most lenders will not proceed, and cash buyers are the realistic market.
The freeholder's counter-notice date, which is at least two months after your notice. The tribunal window, which opens two months after the counter-notice and closes six months after it. And the two months you have to complete the new lease once the terms are agreed or decided, with a further two months to apply to the court if it is not done. Missing any of them means the notice is treated as withdrawn and a new one cannot be served for the flat for twelve months.
Almost never. Withdrawing triggers the freeholder's costs to that point and the twelve-month bar on a new notice, and it throws away your valuation date. A buyer who wanted a flat with an extension in progress now gets a short lease they cannot extend for a year. Assigning the notice is a routine piece of conveyancing and nearly always the better course.
Usually yes, if you can fund the premium and have the time. A completed extension lets you sell a long-lease flat at a long-lease price with no lender complications. From an agreed figure to a completed new lease typically takes four to eight weeks. If the premium is still in dispute, or you need to complete the sale sooner than that, assigning the claim or a simultaneous completion are the alternatives.
Not for a sale in the next year. The parts of the Leasehold and Freehold Reform Act 2024 that would abolish marriage value and grant 990-year terms are not in force, the consultation on the valuation rates closes on 21 October 2026 and a freeholders' legal challenge is listed for the Court of Appeal in April 2027. A buyer prices the flat on today's law. If your lease is near 80 years, serving a notice now protects the valuation date and that protection passes to the buyer.