Can severe damp and mould make a property not suitable for use as a dwelling for SDLT?

Introduction

Buyers sometimes ask whether a badly damaged or unsafe property counts as a “dwelling” for Stamp Duty Land Tax purposes. This matters because SDLT treatment often depends on whether the building was residential at the effective date of the transaction. A common argument is that the property was in such poor condition that it was not suitable for use as a dwelling when bought.

Cases involving damp, mould, structural problems, missing facilities, fire damage or other serious hazards often turn on the same legal question: was the building merely in disrepair, or was it genuinely unsuitable for residential use? That question has become harder for taxpayers to answer in their favour following recent case law.

The Question

The issue was raised in the context of a buyer who purchased a property said to have extensive damp and mould. The argument was that the condition was not just unattractive or in need of repair, but so serious that it created a real health risk and required substantial remedial works. It was also suggested that the defects were serious enough that, under the Housing Health and Safety Rating System, the local authority might have considered enforcement action, potentially including a prohibition on occupation.

The practical question was whether that level of disrepair meant the property was not “suitable for use as a dwelling” on completion, and whether supporting evidence such as photographs, reports, sales particulars and repair evidence would help establish that position.

Nick’s Explanation

Nick’s central point was that the legal test looks at the property’s actual condition at the effective date of the transaction, not whether it could later be repaired. In anonymised form, his reasoning was that:

• extensive damp and mould may go beyond cosmetic disrepair and amount to a genuine health hazard;
• under the HHSRS in the Housing Act 2004, severe damp and mould can amount to a Category 1 hazard;
• where hazards are serious enough that a local authority could issue or justify a prohibition notice, that may support an argument that the property was not suitable for use as a dwelling;
• the distinction is between ordinary repairable defects and defects so fundamental that safe occupation is not realistically possible at completion.

Nick also relied on earlier tribunal authorities such as PN Bewley v HMRC and Fish Homes Ltd v HMRC, which recognised that some buildings can fall outside the concept of a dwelling where the condition is sufficiently serious.

However, any public-facing explanation now has to reflect the later Court of Appeal decision in Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799. That decision means the threshold for showing that a property was not suitable for use as a dwelling is now relatively high.

The Law

The relevant SDLT legislation is in the Finance Act 2003. For these purposes, a “dwelling” includes a building that is used or suitable for use as a single dwelling. The question is usually determined as at the effective date of the transaction, which is commonly completion.

Schedule 4A to the Finance Act 2003 contains the wording often discussed in these cases, especially paragraph 7(1)–(2)(a), which refers to a building that is “used or suitable for use as a single dwelling”. Although the precise statutory context can vary depending on the SDLT issue in dispute, the same wording has generated extensive litigation about what “suitable for use” means.

HMRC guidance has historically accepted that some properties may be unsuitable for use as a dwelling where there are hazards present that would cause a local authority to issue a prohibition notice restricting use of the premises. Guidance can help explain HMRC’s approach, but the legal test is set by statute as interpreted by the courts and tribunals.

The HHSRS under the Housing Act 2004 is also relevant in evidence terms. It does not itself decide the SDLT issue, but it can help show whether defects were serious enough to create a real risk to health or safety. In particular, Category 1 hazards are the most serious hazards under that regime and can trigger enforcement powers.

Analysis

The analysis usually proceeds in stages.

First, identify the condition of the property at the effective date. The legal test is not concerned with what works were planned, what the buyer intended to do later, or how cheaply the building could be restored. The focus is on the actual physical state of the property when the transaction took effect.

Second, separate ordinary disrepair from fundamental unsuitability. Many properties bought for renovation remain dwellings for SDLT purposes. Missing fittings, old kitchens, dated bathrooms, damaged plaster, worn carpets, broken windows, heating issues or general neglect will often not be enough. The courts have repeatedly drawn a line between buildings that need work and buildings that are genuinely incapable of being used as a home.

Third, consider whether the defects created a real danger to health or safety. Severe damp and mould may assist a taxpayer’s case if the evidence shows something more than inconvenience or poor condition. The stronger argument is where the defects were so serious that occupation would have been unsafe, or where expert evidence shows a level of hazard consistent with local authority enforcement action.

Fourth, test the evidence. A claim of unsuitability is only as strong as the documents behind it. Useful evidence may include:

• dated photographs showing the condition at completion;
• surveyor or environmental reports;
• specialist damp, mould, structural or asbestos reports;
• local authority records or notices;
• builder quotations describing the extent of remedial works needed;
• sales particulars describing the property’s condition;
• invoices and work schedules showing the scale of post-completion works.

Fifth, apply the case law. Earlier authorities such as PN Bewley v HMRC [2019] UKFTT 65 (TC) and Fish Homes Ltd v HMRC [2020] UKFTT 180 (TC) were often relied upon by taxpayers arguing that a property had crossed the line from disrepair into unsuitability. Those cases remain relevant, but they must now be read in light of later appellate authority.

The most important modern development is Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799. Following that decision, the condition threshold in “not suitable for use” cases is now relatively high. The Court of Appeal makes clear that the test is not satisfied simply because the property is in very poor condition, requires major works, or contains serious defects that are capable of repair. The question is whether the property had, in substance, ceased to be suitable for use as a dwelling at the relevant date. That is a demanding standard.

So, in an uninhabitable or not suitable for use case, severe damp and mould might still be enough, but only where the evidence shows a very serious level of danger or physical compromise. A taxpayer cannot assume that extensive remediation needs, health concerns, or even significant unpleasantness will automatically take the property outside the definition of a dwelling.

The reference sometimes made to Aldford House Freehold Ltd v Grosvenor (Mayfair) Estate [2019] EWCA Civ 1848 may still be of interpretive interest in some arguments about physical configuration and readiness for occupation. But for SDLT suitability disputes, the Court of Appeal’s decision in Mudan is now the key authority and sets the practical benchmark.

Outcome

A property affected by severe damp and mould is not automatically outside the SDLT definition of a dwelling. The buyer would need strong evidence showing that, at completion, the condition went well beyond repairable disrepair and reached the point where the building was genuinely not suitable for residential use.

Following Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799, that is now a relatively high hurdle. In many cases, even substantial defects and expensive remedial works will not be enough on their own.

Practical Steps

• Gather dated evidence of the property’s condition at the effective date, not just after works began.
• Obtain expert reports where possible, especially where health and safety hazards are alleged.
• Check whether any local authority involvement existed or would realistically have been justified under the HHSRS.
• Compare the defects with the case law, bearing in mind that Mudan now sets a stricter standard.
• Do not rely only on estate agent wording such as “in need of renovation” or “uninhabitable”; those descriptions are not legally decisive.
• Look at whether basic residential function was truly absent or whether the property was simply a poor-quality dwelling needing major repair.
• If making or defending an SDLT claim, organise the evidence chronologically and link each item to the condition at completion.

Conclusion

Severe damp and mould can support an argument that a property was not suitable for use as a dwelling for SDLT purposes, but only in a genuinely serious case supported by strong evidence. After Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799, the condition threshold is relatively high, so the distinction between major disrepair and true unsuitability is now more important than ever.

Legal References Used

• Finance Act 2003, including Schedule 4A paragraph 7(1)–(2)(a)
• Housing Act 2004
• HMRC Stamp Duty Land Tax Manual, SDLTM00385
• PN Bewley v HMRC [2019] UKFTT 65 (TC)
• Fish Homes Ltd v HMRC [2020] UKFTT 180 (TC)
• Aldford House Freehold Ltd v Grosvenor (Mayfair) Estate [2019] EWCA Civ 1848
• Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799

This page was last updated on 22 March 2026.

See all questions and answers categorized in this sitemap. Or use Google site search below.