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Declaring Japanese knotweed when selling: the TA6 form explained

One tick-box on the TA6 Property Information Form causes more post-sale disputes than almost anything else in conveyancing. Here's what the knotweed question actually asks, what each answer commits you to, and how to sell an affected property without it coming back to bite you.

Published July 2026 · 6 min read

The quick version: The TA6 asks whether your property is affected by Japanese knotweed. Answer honestly: "Yes" with a management plan is a sellable position; "No" asserts certainty that no knotweed exists, including roots underground - a claim few sellers can truly make; "Not known" is the honest middle ground if you're unsure. A wrong "No" can cost you a misrepresentation claim years after completion.

The question on the form

In England and Wales, sellers complete the Law Society's TA6 Property Information Form as part of conveyancing. It asks whether the property is affected by Japanese knotweed, with three possible answers: Yes, No, or Not known. If the answer is Yes, you're asked whether there's a management plan in place and for the supporting paperwork.

It looks like a formality. It isn't. Your answers form part of the contractual picture the buyer relies on, and a wrong one has consequences long after the keys change hands.

What each answer really commits you to

Y
"Yes" - knotweed is or has been present. Not the sale-killer people fear. Paired with a professional treatment programme and an insurance-backed guarantee, most lenders will still lend and most sales proceed. Attach the plan and guarantee documents - that paperwork is what buyers' solicitors and surveyors want to see.
N
"No" - you're certain it isn't affected. This is the risky one. "No" doesn't mean "I haven't noticed any" - it asserts the property is not affected at all, and knotweed can be present as dormant rhizome underground with nothing visible, especially in winter or after cutting. If it later emerges and your "No" proves wrong, the buyer has the makings of a claim.
?
"Not known" - the honest middle ground. The right answer when you genuinely don't know. It pushes the question onto the buyer's own survey, which is exactly where uncertainty belongs. Expect a cautious buyer to commission a specialist inspection.

What happens if you get it wrong

If a buyer discovers knotweed after completion and can show your answer was dishonest - or made recklessly, without reasonable grounds - they can bring a misrepresentation claim. Courts have upheld claims like this against sellers who ticked "No", with damages covering treatment costs and the knotweed-related drop in the property's value, plus legal costs. The few hundred pounds a proper survey would have cost is nothing beside that.

Worth knowing: estate agents have their own duty to disclose material information they know about, so telling your agent but not the form isn't a strategy. Consistency and paperwork are your protection.

Selling an affected property well

  1. Confirm what you actually have. Plenty of "knotweed" turns out to be a look-alike. A photo first-check takes seconds, and a confirmed surveyor review settles it properly before you commit an answer to the form.
  2. If it's confirmed, get a management plan. A PCA-member treatment programme with an insurance-backed guarantee is the document set lenders look for - see knotweed & mortgages.
  3. Declare it with the paperwork attached. "Yes, with a funded plan and guarantee" reads as a managed problem, not a mystery. Mystery is what kills sales.
  4. Keep every record. Treatment logs, invoices, guarantee certificates, survey reports - they transfer reassurance to the buyer and protect you afterwards.

Buying rather than selling?

Read the seller's TA6 answer with the same care. "Not known" means check for yourself - especially at a winter viewing, when knotweed is easiest to miss or tidy away. And remember the seller's honesty duty runs to the form; it's your survey that protects you.

Selling, and not sure what that plant is?

Get a fast first check from a photo, then a dated report confirmed by a PCA CSJK accredited surveyor - the answer you need before you fill in the form.

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Frequently asked questions

Is declaring knotweed a legal requirement?

The TA6 itself is standard practice rather than statute, but answering it dishonestly exposes you to a misrepresentation claim - which is very much a legal consequence. There's no requirement to have treated knotweed before selling, only to be honest about it.

Do I have to declare knotweed on a neighbouring property?

The TA6 knotweed question concerns your property. Knotweed nearby can still affect valuations, and buyers' surveyors will look over the fence - so if you know about it, expect it to come up. Our guide to neighbours and knotweed covers who's responsible for what.

What if knotweed appears after I've answered?

Your answer needs to be true when you give it. If knotweed emerges between exchange and completion, tell your solicitor - concealing a known change is exactly the territory claims are made of.

Does Scotland use the TA6?

No - the TA6 is used in England and Wales. Scottish conveyancing works differently, but honesty duties around known defects still apply, and lender attitudes to knotweed are broadly similar UK-wide.

Alexander White, PCA Certificated Japanese Knotweed Surveyor
Written by Alexander White PCA Certificated Japanese Knotweed Surveyor (CSJK) About our surveyors →

This guide is general information, not legal advice, and is a first-step aid rather than a professional survey. For a property sale, mortgage application or dispute, always obtain a confirmed survey from a PCA-accredited Japanese knotweed specialist, and speak to your conveyancer about your specific circumstances.