The 80-year lease threshold is the single most important milestone for any UK leaseholder. Learn how marriage value works and why crossing this line can double your extension cost overnight.
Once the unexpired term on a lease falls below 80 years, a concept called "marriage value" becomes payable as part of any lease extension premium. This can dramatically — and suddenly — increase the cost of extending your lease. It is the single most important financial threshold in leasehold enfranchisement.
Marriage value is the increase in combined value of the leasehold and freehold interests that arises from merging them through an extension. This uplift is split 50/50 between the parties. Above 80 years, marriage value is legally presumed to be zero and is not payable.
Marriage value can add 50–150% to the cost of a lease extension for sub-80-year properties. For a flat worth £400,000, this could mean an additional £20,000–£60,000 on your premium.
Consider a flat valued at £350,000 with ground rent of £200 per year:
Property: £300,000 | Ground rent: £250/yr
At 79 years: premium approximately £12,400
At 78 years: premium approximately £14,200
Cost of waiting one year: approximately £1,800 extra — plus your lease is now one year shorter and less mortgageable.
The 2024 Act proposes abolishing marriage value but requires secondary legislation with no confirmed date. Your lease shortens every day you wait. Consult a surveyor to model both scenarios before deciding — for most people, acting now is the safer financial decision.
Most high-street lenders require at least 70–85 years remaining at mortgage application. A flat with 65 years remaining often fails standard mortgage checks, making it very hard to sell and significantly reducing its marketability and value.
The 80-year rule means that when a lease falls below 80 years remaining, the cost of extending it rises sharply because a legal concept called marriage value becomes payable. Marriage value is 50% of the gain created by merging the leasehold and freehold interests. Most mortgage lenders also require at least 80 years remaining, so falling below this threshold can make a property unmortgageable.
On a £400,000 flat, extending from 81 years might cost £6,000–£10,000. The same extension from 75 years could cost £20,000–£35,000 — the difference being marriage value. The shorter the lease below 80 years, the greater the marriage value component and the more expensive the extension.
The Act proposes to abolish marriage value entirely, which would eliminate the 80-year cliff effect. However, this provision requires further secondary legislation and has no confirmed implementation date. Until it takes effect, the 80-year rule remains in force and leaseholders approaching 80 years should act promptly.
You should instruct a RICS-qualified surveyor to value a lease extension premium immediately. The closer you are to 80 years, the more urgently you need to act — every month below 80 years increases marriage value. Use our free calculator to get an instant estimate before consulting a surveyor.
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Calculate Now →This article is for general information only and does not constitute legal or financial advice. Always consult a specialist solicitor and RICS surveyor before taking any action.
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