Lease Extension Cost Calculator (UK) | Ready Steady Sell
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Lease Extension Cost Calculator

Quick answer

Get an indicative cost of extending the lease on a flat under the statutory route (90 extra years, ground rent reduced to zero). The premium depends mainly on the years remaining, the flat value and the ground rent — and rises sharply once the lease drops below 80 years.

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Indicative estimate only. The true premium is set by a RICS valuation using current market deferment and capitalisation rates, relativity, and (below 80 years) marriage value. The Leasehold and Freehold Reform Act 2024 is expected to change how premiums are calculated. Always get a professional valuation before serving notice.

What drives the cost of a lease extension

Under the statutory route a leaseholder can add 90 years to the lease and reduce ground rent to a peppercorn (zero). The premium you pay the freeholder is made up of three parts: the capitalised ground rent they give up, the reversion (the value of getting the flat back, deferred far into the future), and — crucially — marriage value if the lease is under 80 years.

The 80-year cliff edge

Once a lease drops below 80 years, "marriage value" becomes payable and the premium jumps significantly — often by thousands. If your lease is close to 80 years, it is usually far cheaper to act before it crosses that line.

Short lease and don't want the hassle?

Extending a lease takes time and money. If you would rather just sell, a short lease puts many buyers (and their mortgage lenders) off — but it is exactly the kind of property our vetted cash buyers purchase as-is, with no need for you to extend first. Compare offers and weigh it against the cost above.

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Frequently asked questions

Straight answers, no sales talk

How much does it cost to extend a lease?

The premium depends mainly on the years remaining, the flat value and the ground rent. It is made up of the capitalised ground rent, the reversion, and — below 80 years — marriage value, which can add thousands. Use the calculator for an indicative figure and get a RICS valuation before serving notice.

Why is 80 years important for a lease?

Once a lease falls below 80 years, "marriage value" becomes payable and the cost of extending jumps significantly. It is usually much cheaper to extend before the lease crosses 80 years.