Can a contaminated or unsafe property qualify for non-residential SDLT?

Introduction

Buyers often ask whether a run-down, contaminated or unsafe dwelling can be treated as non-residential for Stamp Duty Land Tax (SDLT). The reason is simple: if a property is genuinely non-residential at the effective date of the transaction, the SDLT treatment may be different and, in some cases, cheaper than residential rates.

This question usually comes up where a property has a serious history of damage, contamination or disrepair and is being sold at auction. The key issue is not whether the building is unattractive, difficult to mortgage or expensive to fix. The real question is whether it was suitable for use as a dwelling at the relevant date. That threshold is now relatively high following Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799.

The Question

A prospective buyer was considering an auction purchase of a property said to have contamination issues and an unusual history. The buyer wanted to know whether there might be any SDLT saving on the basis that the property was not habitable, and therefore might be treated as non-residential rather than residential.

Nick’s Explanation

Nick’s explanation, in substance, was that the SDLT position depends on the condition of the property at completion and on whether the building is properly characterised as residential or non-residential under the legislation.

He pointed the buyer to material on habitability and explained that where a purchaser wants to treat a dwelling as non-residential at completion, the condition evidence and the way the point is presented to the conveyancing solicitor matter.

In anonymised form, the key message was:

The question is whether the property can genuinely be assessed as non-residential at completion. That depends on the facts and the legal test for suitability for use as a dwelling, not just on contamination or a difficult history.

That is an important distinction. A contaminated site does not automatically cease to be residential for SDLT. Nor does a house become non-residential simply because it needs major works, has been vacant, or is sold in poor condition.

The Law

SDLT is charged under the Finance Act 2003. For these purposes, the starting point is whether the subject matter of the transaction is “residential property” or “non-residential property”.

Broadly, residential property includes:

• a building that is used or suitable for use as a dwelling, or is in the process of being constructed or adapted for such use;
• land that forms part of the garden or grounds of such a building; and
• interests or rights over land that benefit such a dwelling.

If the property is not residential property, it is generally treated as non-residential property.

The phrase “suitable for use as a dwelling” has been heavily litigated. The courts have made clear that the test is applied to the property’s physical condition at the effective date of the transaction, usually completion. The focus is on suitability for use as a dwelling, not on the buyer’s intended works or future plans.

Recent authority has tightened the position. In particular, the Court of Appeal in Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799 confirmed that the threshold for showing a dwelling is not suitable for use as a dwelling is relatively high. Serious defects are needed. Ordinary disrepair, outdated condition, lack of modernisation, or even substantial refurbishment needs will often not be enough.

Analysis

When looking at a contaminated or damaged property, the SDLT analysis usually works in the following order.

First, identify what is being bought. If the transaction includes land and a building that appears to be a house or other dwelling, HMRC will usually start from the position that it is residential unless the facts clearly point the other way.

Second, look at the condition of the building at the effective date of the transaction. The relevant question is whether the building was suitable for use as a dwelling on that date. This is a factual and legal question. Evidence may include:

• survey reports;
• environmental reports;
• photographs and videos;
• auction legal pack documents;
• evidence of structural failure or statutory prohibition on occupation;
• evidence that essential living facilities were absent or unusable.

Third, separate contamination from habitability. Contamination may be highly relevant, but only if it affects the building’s suitability for use as a dwelling in a real and serious way. For example, contamination that creates an actual inability safely to occupy the dwelling may help. But contamination that mainly affects value, financing, future development, or remediation cost does not automatically make the property non-residential.

Fourth, apply the high threshold now confirmed by Mudan. The courts are not asking whether a reasonable buyer would want to live there, whether a lender would lend, or whether the property needs extensive works. They are asking whether it is suitable for use as a dwelling. That means many distressed properties remain residential for SDLT even though they are unattractive purchases.

Fifth, consider whether there is some other non-residential feature. In some cases, SDLT savings arise not from lack of habitability but because the property is mixed-use or includes non-residential land. That is a separate analysis. The mere fact that a property has a commercial history, contamination, or development potential does not by itself make it mixed-use.

In practice, a buyer at auction should be cautious. Auction purchases create a binding contract quickly, often with limited time to review evidence. If the SDLT filing position is going to depend on arguing that a dwelling was not suitable for use as a dwelling, the evidence should be assembled before bidding if possible.

Outcome

The practical conclusion is that a contaminated property does not automatically qualify for non-residential SDLT. The buyer only has a credible non-residential argument if the condition of the property at completion was so serious that it was not suitable for use as a dwelling under the statutory test.

Following Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799, that threshold is relatively high. A property may be contaminated, neglected or in very poor repair and still remain residential for SDLT.

Practical Steps

If you are assessing a similar purchase, the sensible next steps are:

• obtain the auction legal pack and review it before bidding;
• commission or review a survey dealing with physical condition and occupation suitability;
• obtain any environmental or contamination reports;
• gather dated photographs and videos showing the condition at the relevant time;
• check whether there were any statutory notices, prohibition notices, or other official restrictions on occupation;
• ask whether the building had functioning essentials for residential occupation, such as structural integrity, water, sanitation and safe access;
• consider whether the argument is really about non-habitability or whether mixed-use may be the true issue;
• ensure the SDLT position taken in the return matches the evidence available at completion.

If the claim is that the property was not suitable for use as a dwelling, the evidence should be specific and contemporaneous. General statements that the property was contaminated, notorious, difficult to insure, or in need of refurbishment are unlikely to be enough on their own.

Conclusion

A buyer may obtain different SDLT treatment only if the facts support a proper legal conclusion that the property was non-residential at the effective date. In an uninhabitable or not suitable for use case, the test is now demanding. After Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799, only genuinely severe condition issues are likely to take a dwelling outside the residential SDLT rules.

Legal References Used

• Finance Act 2003
• Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799

This page was last updated on 22 March 2026.

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