Lease Extension Calculator

Online lease extension calculators give you a bracket, not an answer. They work from three
inputs — the unexpired term, the ground rent and a rough capital value — and they cannot see the
things that actually move the number on a real flat: the tenure of the block, the internal
condition, whether there is a defective lease, what has sold locally in the last six months, and
what the freeholder’s valuer will argue for. Use the method set out below to sanity-check any
figure you have been given, then get a formal valuation before you serve notice.

The three components of a lease extension premium

Under the Leasehold Reform, Housing and Urban Development Act 1993 a qualifying leaseholder
of a flat can extend by 90 years with the ground rent reduced to a peppercorn. The premium is
built from:

• The value of the lost ground rent — the income stream the freeholder gives
  up, capitalised at a yield the market and the tribunals accept.
• The reversion — the present value of the freeholder eventually getting the
  flat back, discounted over the remaining term.
• Marriage value — where the lease has under 80 years left, half of the uplift
  in value created by the extension is payable to the freeholder. This is the cliff edge that makes
  80 years the number everyone watches.

Why 80 years matters so much

At 81 years unexpired there is no marriage value. At 79 there is, and the premium typically
jumps sharply — often by several thousand pounds on an otherwise identical flat. If your lease
is anywhere near 80 years, the cost of waiting is measured in months, not years.

Indicative premium ranges

Ranges below are typical UK market fees for the work described, shown so you can budget. They are not a quotation. We give a fixed, written fee for your specific property before any work starts.

Unexpired term	Marriage value applies?	Typical premium as % of flat value
95 years +	No	Roughly 1% to 2%
90 years	No	Roughly 2% to 3%
85 years	No	Roughly 3% to 4%
82 years	No, but close	Roughly 4% to 5%
79 years	Yes	Roughly 7% to 9%
70 years	Yes	Roughly 10% to 13%
60 years	Yes	Roughly 16% to 20%

Those percentages assume a modest ground rent. A rent that doubles every ten or fifteen years,
or one that has already passed the £250 threshold outside London, changes the calculation
materially and can make the flat difficult to mortgage in its own right.

A worked example

A two-bedroom flat with a long-lease value of £260,000, 78 years unexpired and a ground rent of
£150 rising every 25 years. Capitalising the rent gives a few thousand pounds. The reversion over
78 years discounts to a small figure. Marriage value is the substantial element: the difference
between the extended and unextended values, halved. On numbers of that shape the premium lands in
the region of £18,000 to £22,000 before costs — but a valuer who can evidence recent unextended
sales in the same block will argue that range up or down by thousands.

What is not in the premium

You also pay the freeholder’s reasonable valuation and legal costs, plus your own valuation and
conveyancing. Budget for those separately; they are not optional and they are not included in any
online calculator.

Get a valuation you can rely on

We are RICS registered valuers and we produce lease extension valuations for leaseholders across
Canterbury and Kent — the figure you serve your section 42 notice at, the range you should be
prepared to negotiate within, and the evidence to support both. Where the freeholder disputes it,
we can act through to a First-tier Tribunal determination.

Frequently asked questions

Are online lease extension calculators accurate?

They are a starting bracket. They cannot see relativity evidence, condition, defective lease clauses or local comparables, all of which move the premium.

Can I extend a lease with under 80 years without paying marriage value?

No. Marriage value is payable once the unexpired term falls below 80 years and there is no way round it under the statutory route.

How long does a statutory lease extension take?

Typically six to twelve months from serving notice, longer if the premium goes to tribunal.

Do I have to own the flat for two years?

Yes, for the statutory route. An informal deal with the freeholder can be done at any time but carries none of the statutory protections.