Japanese knotweed and UK mortgage lenders: the 2026 policy update
Where each of the major UK lenders stands on Japanese knotweed in 2026, including the new RICS 2022 guidance interpretations and category-based risk decisions.
Mortgage lender policy on Japanese knotweed has settled considerably since the RICS Information Paper was updated in 2022. By 2026, the position of the major UK lenders is now broadly predictable — but the detail still matters, and a buyer asking the right questions of their surveyor and broker can close a sale that an unprepared one would lose.
The 2026 baseline: RICS categories
Surveyors now classify knotweed into one of four management categories rather than the older risk bands. Categories A and B (small stands away from buildings) are generally lent on with a noted plan; categories C and D (close to structures, or affecting amenity) require an active management plan with an IBG before most lenders will progress.
Who lends in 2026
- Halifax — lends with an IBG and documented plan, category A–D.
- Nationwide — same as Halifax; specifically references RICS 2022 categories in valuation guidance.
- Santander — accepts management plans from PCA member contractors.
- Barclays — IBG required for any category C or D.
- NatWest / RBS — case-by-case, generally lenient with proper documentation.
- HSBC — IBG required, no in-house exclusion list.
- Principality (Wales) — historically strict, now aligned with Halifax/Nationwide.
- Skipton, Coventry, Yorkshire — lend with IBG, may decline category D within 3 m of dwelling.
Who still declines
A small group of regional building societies and some bridging/specialist lenders will decline any property with active or recent knotweed regardless of paperwork. If your buyer is using one of these, the workaround is normally to refer them to a mainstream lender — every broker we work with can identify the policy in under five minutes.
What the paperwork pack must contain in 2026
- PCA-certificated survey report with RICS 2022 category classification.
- Written management plan with method statement and treatment schedule.
- Insurance-backed guarantee (5 or 10 year) — assignable to successive owners, with the underwriter named.
- Treatment records to date (if a programme has started).
What changed between 2025 and 2026
Two lenders that previously asked for a 10-year IBG as standard now accept a 5-year IBG on category A and B properties — bringing the cost of unlocking a sale down by around £400 on a typical domestic case. The trade-off is that 5-year IBGs need to be renewed if the property is re-sold after the term expires.
Frequently asked questions
- Will a 2026 mortgage application be rejected purely because knotweed is mentioned in the TA6?
- No — provided there is a documented management plan and an assignable IBG. The major lenders see this as a managed risk, not a deal-breaker.
- Does the IBG transfer to my buyer when I sell?
- Yes. Every IBG we issue is assignable to successive owners at completion with no transfer or assignment fee.
- Can I get a mortgage if the seller has only just commissioned a survey?
- Yes — most lenders accept a signed contract and start-date for the programme, provided the IBG is issued before completion.
Reviewed by
The survey team
PCA-certificated surveyors, Japanese Knotweed Elimination
PA1 / PA6A certificated surveyors who carry out the site visits, write the management plans and sign off the reports issued to lenders and solicitors.
Reviews the technical, legal and lender statements in this article.
What this page can't tell you
- Guidance is general. Identification, treatment choice and timescales can only be confirmed by a site visit — photographs alone are indicative.
- Lender and insurer requirements vary by institution and change over time. We state what is typically accepted, not what any named lender will accept on your case.
- Guarantee (IBG) eligibility depends on the plan chosen, the survey findings and the underwriter's acceptance. It is not automatic.
- Legal points summarise published law and guidance current at the review date. They are not legal advice.
Last reviewed · Questions on anything stated here: 07582 869979
Think you've found knotweed? Send us a photo.
Free written identification from a PCA-certificated surveyor — no obligation.
Free identification