At what lease length does it become much more expensive to extend?

The most significant threshold is 80 years. Once a lease falls below 80 years, marriage value becomes payable under current legislation, typically adding 50% or more to the premium. The tribunal data shows a near-doubling of the median premium between leases just above 80 years (£7,046 median) and those in the 70–79 year band (£12,622 median). A second significant threshold is approximately 60 years, below which premiums accelerate further and mortgage difficulties begin.

Why is the mean so much higher than the median for very short leases?

The under-40-year band includes a small number of central London properties with extremely short leases on very high-value flats, producing premiums above £1 million. These exceptional outcomes pull the mean (£468,962) far above the median (£236,988). The median is a more representative guide for most properties in this range.

What happens to lease extension cost for leases below 40 years?

Below 40 years, lease extension premiums in the tribunal data are extremely high, with a median of £236,988 and cases reaching above £2.9 million. Properties with fewer than 40 years remaining also face mortgage difficulties, meaning most lenders will not offer standard residential mortgages. Extension at this stage is often essential rather than optional, and the cost reflects both the large marriage value component and the near-term reversion.

Should I extend my lease now or wait until I can afford it?

The tribunal data shows that costs rise substantially as lease length falls, particularly below 80 years. Waiting one year on a lease at 81 years remaining may not significantly increase the premium, but waiting several years into the 70s can add tens of thousands of pounds to the cost. This analysis is based on aggregate tribunal data and cannot account for your specific property, valuation evidence or circumstances. We recommend obtaining professional valuation advice to assess the cost of waiting in your specific situation.

Are there any lease lengths where extension is not worth it?

The tribunal data does not address this question directly — every case in the dataset involved a lease that was worth extending. However, for leases approaching zero years remaining, the cost of extension can in some cases exceed the uplift in property value from the extension, making the exercise economically questionable. Professional advice from an enfranchisement valuer is essential for any property with fewer than 50 years remaining.

Lease Extension Cost by Lease Length

Median premium — 70–79 years remaining

£12,622

103 tribunal decisions

Median premium — 60–69 years remaining

£23,463

213 tribunal decisions

Median premium — under 40 years remaining

£236,988

63 tribunal decisions

How premiums change with lease length

The relationship between lease length and premium is not linear — it accelerates sharply at two key thresholds: 80 years and approximately 60 years. Above 80 years, premiums are comparatively modest because marriage value does not apply and the reversion is far in the future. Below 80 years, marriage value becomes payable and costs begin to rise steeply. Below 60 years, the rate of increase accelerates further as the reversion value grows and the lease becomes increasingly problematic for mortgage lenders.

Across 595 tribunal decisions with both term and premium data, the median premium almost doubles between the 70–79 year band (£12,622) and the 60–69 year band (£23,463), and nearly doubles again between 60–69 years and 50–59 years (£41,384).

Years remaining	Decisions analysed	Median premium	Mean premium	Largest premium
Under 40 years	63	£236,988	£468,962	£2,931,089
40–49 years	41	£47,300	£77,545	£366,870
50–59 years	136	£41,384	£59,747	£548,300
60–69 years	213	£23,463	£28,793	£235,000
70–79 years	103	£12,622	£14,201	£38,517
80–89 years	30	£7,046	£7,813	£30,580

Source: LeaseIntel Tribunal Database

Sample: 595

Period: 2005–2025

The 80-year threshold in the data

The jump between the 80–89 year band (median £7,046) and the 70–79 year band (median £12,622) represents a near-doubling of the typical premium — and this is the crossing of the 80-year threshold where marriage value first becomes payable under current legislation.

This is the clearest finding in the entire LeaseIntel dataset: once a lease falls below 80 years, the median premium increases by approximately 79% compared with leases just above that threshold. For a property worth £400,000, the difference between extending at 81 years versus 79 years remaining can represent a premium increase of £15,000–£25,000 or more.

Very short leases: the extreme end

The under-40 year band shows a median premium of £236,988 — nearly ten times the 70–79 year median. These cases typically involve properties in prime central London with extremely short unexpired terms, where the combination of high property values, substantial marriage value, and a near-term reversion produces very large premiums.

The mean premium for under-40-year leases is £468,962 — nearly double the median — reflecting a small number of exceptional central London cases above £1 million. Properties with fewer than 40 years remaining also face significant mortgage difficulties, making extension not optional but essential for sale or remortgage. This urgency is reflected in the tribunal outcomes.

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Frequently asked questions

Methodology

LeaseIntel analyses published First-tier Tribunal (Property Chamber) decisions on lease extension premiums. Each decision is parsed into a structured record covering unexpired term at the valuation date, property value, ground rent profile, deferment and capitalisation rates, marriage value treatment and the final premium determined.

Analyses only include decisions containing the specific lease-term and valuation data required for that study.
Cases are grouped by unexpired term at the valuation date (not the date of the decision).
Sample sizes vary between analyses because not every decision records every variable.
Small sample groups are flagged with a confidence indicator and interpreted cautiously.
Where decisions span multiple flats or hearings, each lease is treated as a separate observation.

Caveats

Tribunal decisions represent disputed cases rather than the entire market.
Not all decisions contain every data field.
Sample sizes vary by analysis.
Small sample groups should be interpreted cautiously.

Benchmark your quote

These figures are based on 595 tribunal decisions covering lease lengths from under 40 years to over 80 years. Your own premium depends on your specific lease length, property value, ground rent terms and the valuation evidence available. LeaseIntel compares your circumstances with similar tribunal decisions to provide a personalised benchmark.

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Independent · Not a valuation or legal advice · Tribunal outcomes, not formula estimates