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Japanese Knotweed Law and Tax

Japanese Knotweed - a legal perspective

Japanese Knotweed Consultancy

We work closely with lawyers specialising in Japanese knotweed disputes. The following article has been kindly prepared by Robert Twining (Head of Property Litigation Team) at Warners Law LLP to give you an overview of the current law relating to Japanese knotweed.

The presence of Japanese Knotweed can have legal implications and consequences for neighbours, landlords, tenants, buyers and sellers of land and houses.

In the case of Japanese Knotweed spreading from one owner’s land to a neighbour’s land the landowner could face a legal claim by the neighbour. This is because under the common law of nuisance a landowner must take reasonable steps to prevent a nuisance which may cause damage spreading from his land to neighbouring land. Generally liability will only arise after the owner has been made aware or should have reasonably been aware of the problem. However, there is a legal argument which could be made to suggest that where the Japanese Knotweed has been brought on to the land by the landowner and spreads to the neighbouring land he has a strict liability to his neighbour irrespective of whether the steps he has taken to prevent it from spreading have been reasonable or not.


...A landowner must take reasonable steps to prevent a nuisance which may cause damage spreading from his land to neighbouring land...

In either case, the claim is likely to be for damages for the cost of eradicating it from the neighbouring land and/or an injunction forcing the landowner to take steps in regard to its treatment.

In the case of landlords and tenants, depending on the wording of the lease and also whether the Japanese Knotweed was present when the lease was entered into, a tenant may find himself unwittingly liable to his landlord under the terms of his lease to have any Japanese Knotweed on the demised property treated or removed.

Care must also be taken by a seller when answering enquiries before contract raised by a buyer. This is because he may become liable to the buyer if he makes a misrepresentation, sometimes even innocently and certainly if he has not made reasonable endeavours to check the position before giving answers.

There are potential criminal sanctions under the Wildlife and Countryside Act 1981 under which it is an offence to cause or allow Japanese Knotweed to grow in the “wild” although there is some legal debate as to whether “private land” constitutes the “wild” for the purposes of the Act.

There are also powers under the Town & Country Planning Act section 215 for Local Authorities to force landowners to clear up land if it detracts from local amenities, including that infested by Japanese knotweed. The Town & Country Planning Act is also often used by Local Planning Authorities by way of planning conditions to force developers to remediate sites infested with knotweed.

Finally, the Environmental Protection Act 1990 includes provisions including a “duty of care” for the storage, processing, treating and disposal of controlled waste. Japanese knotweed and the soils it infests are considered to be a controlled waste.

japanese knotweed law

Download the article within Environment Industry Magazine by Robert Twining from Warners Solicitors regarding Japanese Knotweed and the law here



Japanese Knotweed Tax Relief

Land Remediation Tax Relief, known as LRTR, was introduced under the Finance Act 2001 for all companies involved in the remediation of contaminated land, whether for commercial or residential purposes. LRTR is available at 50% for developers (i.e. those trading in property), whilst property investors or owner occupiers can benefit from 150% relief against their qualifying expenditure.

Japanese Knotweed Consultancy

The legislation currently permits any expenditure that prevents, minimises, remedies or mitigates the risk of any harm being done to people, property or the wider environment. The harm, or potential to cause harm, must be as a result of a substance or substances in, on or under the land to be applicable. “Substances” include for example heavy metals, hydrocarbon contamination and, arguably Japanese knotweed.

Environet works with specialist Tax Consultants to claim the tax that is rightfully yours on a no win no fee basis for all Japanese knotweed remediation undertaken since May 2001. Contact us for further details.

Landfill Tax is now charged generally at the higher Landfill Tax rate for disposal of contaminated soils following the removal of the exemption in 2008, significantly increasing the cost of the dig and dump solution.

Environet’s Xtract method for the on-site remediation of land infested with Japanese knotweed not only avoids the punitive costs of Landfill Tax but is also eligible for relief under LRTR.

Useful Links

Environet on BBC One Show

Managing Japanese Knotweed on Development Sites – Code of Practice published by Environment Agency (5.5MB)

Japanese Knotweed – A Guide for Landowners and Developers published by Environet

Knotweed online Survey Form Fill out your details and we will send a quote

Japanese Knotweed – A Legal Perspective by Robert Twining, Warners Solicitors

Xtract Method Info published by Environet

knotweed leaf

Xtract™ - on site remediation for rapid guaranteed eradication of Japanese knotweed. More info


herbicide method

Herbicide treatment for the eradication or control of Japanese Knotweed. Suitable for commerical, residential and development sites. More info