Analysis of 6.5 Million Lease Records Highlights Short-Lease Mortgage Risks

Around one in 12 residential leases in a major analysis of property records had between 80 and 90 years remaining, putting a substantial group of flat owners within sight of decisions that could affect their next mortgage, sale or lease extension.

Fresh commentary from the Open Data Institute and Leasehold Advisory Service, published by Mortgage Solutions on 9 November, also highlights a less visible obstacle: the records used to establish a lease’s remaining life can be inconsistent or lag behind legal changes.

For buyers, this can turn an apparently straightforward purchase into a more complicated financing exercise. A strong income and substantial deposit do not settle whether a lender will accept the flat itself.

The underlying finding was published by LEASE in August. This week’s commentary renews attention on the evidence and its data problems; it does not announce a new mortgage rule or change in leasehold law.

A digital record may not tell the whole story

The ODI’s technical report describes a June 2026 dataset assembled by removing duplicates, excluding identifiable commercial leases and interpreting lease terms recorded in different formats.

The researchers identify important limits. Some entries could not be interpreted reliably, some non-residential records may remain, and an extension awaiting registration might not yet appear in the data.

Those findings have a practical consequence. An owner who says the lease has been extended may have documentation that needs reconciling with the register. Equally, a property listing that describes the original lease as 99 years does not establish how many years remain today.

The conveyancer needs to establish the actual position from the lease, title and any relevant deeds. Discovering a discrepancy after a valuation or mortgage offer has been arranged can mean further questions, revised paperwork and delays for everyone in the chain.

Why 90 years is not a universal mortgage cut-off

Mortgage lenders set different requirements for leasehold security. Some focus on the years remaining when the application is made; others also require a minimum period to remain after the mortgage ends.

The amount borrowed relative to the property’s value can matter too. Nationwide’s published criteria for England and Wales specify at least 55 years at application and 30 years beyond the mortgage term. For borrowing above 85% LTV, its minimum rises to 90 years at application.

Those are selected criteria, with separate new-build rules and a valuation assessment still required. They demonstrate why the same flat can produce different answers depending on how its purchase is financed.

Consider an existing flat valued and priced at £400,000 with 88 years remaining. A buyer with a £40,000 deposit needs a £360,000 mortgage, or 90% LTV. Under that higher-LTV rule, the lease would be too short.

Increasing the deposit to £60,000 reduces the loan to £340,000 and LTV to 85%. That removes this particular 90-year requirement, although it does not establish that the application will be accepted. The additional £20,000 is a real cash requirement, not a technical adjustment every buyer can make.

The separate cost threshold at 80 years

The significance of 80 years comes from lease-extension valuation as well as mortgage availability. Under current rules, marriage value can become part of the premium for a statutory flat lease extension where 80 years or fewer remain when the Section 42 notice is served.

LEASE explains that marriage value concerns the increase in the combined value of the leaseholder’s and landlord’s interests following an extension. The landlord receives half of that increase through the calculation. It is one component of the price, not a fixed surcharge or half the flat’s value.

This gives an owner approaching the threshold a timing issue. Waiting until a sale is agreed or a fixed mortgage is about to expire can leave less room to obtain valuation advice, consider the options and organise the money required.

A lease can cross the threshold during a fixed mortgage

Take an owner whose flat has 83 years remaining when they arrange a five-year fixed mortgage. Without an extension, the lease will have around 78 years left when that deal ends.

The mortgage payment may have been predictable throughout, but the property’s lease position has continued to change. At renewal, another lender may assess a different remaining term and a different valuation.

That does not mean the owner must extend immediately or that a remortgage will be refused. It does mean the lease should form part of the decision at the start of the fixed period, rather than becoming an unexpected issue at the end.

The same applies to someone buying a flat they expect to sell in several years. A mortgage available today does not guarantee that their eventual buyer will have the same choice of lenders or deposit.

Announced reforms have not removed every current cost

Reform headlines can make the decision harder. LEASE’s guidance updated on 5 November lists the abolition of marriage value and 990-year statutory extensions among measures not yet implemented.

The two-year ownership requirement has already been removed. However, that does not bring the remaining reforms into force or make every extension cheaper now.

Waiting may be worth considering for some owners, while others need to sell or refinance before further changes arrive. The useful comparison is between the current extension estimate, the owner’s transaction timetable and the consequences of delay. A promised future saving cannot be treated as an agreed price.

Can the extension and mortgage complete together?

There can be a route through a transaction where the existing lease is too short for the proposed lender. Halifax’s criteria, for example, generally require 70 years at application but allow consideration of shorter leases being extended beyond that point as part of an eligible purchase, remortgage or further advance.

The extension must complete on or before the mortgage, with the offer reflecting that condition. This creates a possible financing route, rather than permission to complete first and resolve the lease later.

The practical question is how the payments fit together. The extension premium, professional fees and purchase costs must be covered, and any borrowing needs to be assessed against the valuation and the borrower’s finances.

A lower purchase price alone does not solve this. A buyer may negotiate a discount that recognises the short lease but still be unable to obtain the mortgage needed to complete. Price, extension terms and funding have to work as one transaction.

Earlier checks can prevent a late financing surprise

LEASE’s free calculator offers a starting point for checking lease length and obtaining an indicative extension cost. A transaction still requires the underlying documents and property-specific advice.

For estate agents and sellers, establishing the remaining term before marketing helps buyers assess the property realistically. For owners approaching remortgage, checking it alongside the existing loan’s expiry date leaves more time to investigate any restriction.

Ground rent and service charges also belong in the affordability assessment. A flat with an acceptable lease length can still stretch the buyer’s budget once those regular costs are added to the mortgage payment.

For Willow, the useful starting information is straightforward: the confirmed lease term, proposed borrowing, property value and whether an extension is being considered or has already been agreed. The solicitor and specialist valuer can establish the legal and valuation position while the mortgage options are assessed.

The research gives scale to a problem that is often discovered one flat at a time. Checking the lease early can reveal whether the obstacle is a particular lender’s criteria, the funding needed for an extension or simply a record that needs clarification.