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How to calculate the cost of a lease extension

We have come up with this quick and easy cost of an extension calculator to give you an indication of the likely cost of your lease extension. Simply fill out the required information and our easy to use calculator which can be used on residential lease extension calculator and buy to let properties wich will produce an estimate and is for guidance purposes only.

Our calculator is not the considered opinion of a Chartered Surveyor.

We are using the parameters of relativity following the general guidance of the RICS Research Document 2009 on graphs of relativity.

How Much Will My Lease Extension Cost?

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Existing Lease Value {{leaseInfo.currentLeaseValue | currency:"£":0}}
Long Lease Value {{leaseInfo.longLeaseValue | currency:"£":0}}
Ground Rent {{leaseInfo.groundRent | currency:"£":0}}
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Leases of this length are prone to more intense negotiations and disputes, as the premium is high - relative to the long lease value. The range of premiums should be considered with that in mind.


The leasehold extension cost calculator will give you a general guide to costs for renewing a lease, but it cannot give you the actual costs.

You should not use this information in tribunal or court proceedings and neither should you take any other action based on this information without first getting professional advice.

This is a summary about valuations under the Leasehold Reform, Housing and Urban Development Act 1993 (as amended), you should remember that the law and the way property is valued can change over time.

Lease Extensions

Owners of leasehold properties must thoroughly understand the lease extension process, because renewing a lease is often a crucial part of maintaining a leasehold property’s value. Even homeowners who have many years remaining on their lease should make sure they fully grasp the implications of a lease running short, and understand how and when they should seek a leasehold extension.

Our lease extension and freehold calculator is designed to give homeowners a rough idea of how much it would cost to renew the lease on their property. This tool is no substitute for the considered opinion of a Chartered Surveyor, however, and anyone considering a leasehold renewal should seek professional advice.

Who Might Need A Leasehold Extension?

If your property is a flat it is almost certainly owned under a leasehold agreement, which means that although you might own the interior space of your own home, the property’s freeholder owns the building itself. As a leaseholder, you have several responsibilities to the freeholder, mainly paying annual “lease ground rent” which you can use a ground rent calculator for to get an idea of costs such as service charges for the upkeep and maintenance of the building, an agreement which continues for the duration of your lease. Most new properties come with a leasehold of 125 years, but if you purchased the property from someone else you may have significantly less than this.

125 years sounds like more than enough time to grow old in a property, and consequently many people write off lease extensions as something they’ll never need to consider. However, although the lease itself will only expire when it reaches 0 years, it becomes more and more expensive to renew once it passes the 80-year mark; past this point, a lease renewal can easily cost tens of thousands of pounds. Therefore, although a homeowner won’t lose control of the property until the lease expires, it should actually be renewed well before it reaches 80 years.

Because leases become so expensive to renew once they pass the 80-year mark, properties with a short lease are hard to sell. In fact, few banks will mortgage a property with fewer than 75 years on the mortgage, so if a property falls below this threshold it becomes even trickier to sell.

This increased expense is reflected in our leasehold extension calculator; less than 60 years on the lease makes it very expensive to renew, and the significant increase in cost becomes evident when using our lease price calculator. HMRC may need to be informed of any capital gains from in property value, and a qualified financial advisor should be consulted to identify any tax liabilities.

How Much Does it Cost to Renew a Lease?

The cost of a lease extension is directly tied to the value of the property. Once the lease falls below 80 years, the landlord is entitled to receive 50% of the increase in property value when an extension iss granted; this “Marriage Value” is what makes it so costly to extend a shorter lease. For example, if a property will gain £20,000 in value from a lease extension, £10,000 of this must be paid to the landlord during the leasehold renewal.

In addition to the costs of renewing the leasehold, homeowners should factor in other expenses such as the legal costs of solicitors and surveys. The tenant must pay their freeholder’s legal fees as well as their own, so these charges can add up to a significant amount.

How Long Does it Take to Extend a Lease?

As a leaseholder, you are entitled to negotiate with your freeholder at any point. If the two of you can reach an agreement informally then it can be a lot quicker to process. However, with an informal negotiation like this the freeholder is under no obligation to agree to any terms, and may charge whatever they feel necessary for the extension.

Leaseholders are entitled to a formal lease extension under the 1993 Leasehold Reform Act, which gives anyone who’s owned a leasehold property for more than 2 years the right to extend their lease. A formal lease extension like this is kept to a strict timeline, and once the Section 42 notice lease extension is served the freeholder has 2 months to respond. Following their response, there is a period of up to two months’ negotiation; if an agreement is not reached, a Leasehold Valuation Tribunal may be sought, which will compel a new lease to be drawn up and enacted within another 2 months.

Mortgage Calculators

We have a range of calculators to help make things simpler for you, from calculating payments to understanding how much your stamp duty may be. These calculators are for guidance purposes only.


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