Can later fencing or repair works affect Multiple Dwellings Relief for an annex?

Introduction

Buyers often ask whether later works to a house and annex can help or harm a claim for Multiple Dwellings Relief (MDR) for Stamp Duty Land Tax (SDLT). A common concern is whether changes made after purchase, such as fencing, patio replacement, or installing a door, might show that there were really two separate dwellings, or instead trigger a problem with HMRC.

This issue usually turns on two questions. First, did the property include more than one dwelling at the effective date of the transaction? Second, did anything happen afterwards that reduced the number of dwellings and created a disqualifying event under Schedule 6B to the Finance Act 2003?

The Question

The general scenario is this. A buyer purchased a property said to include a main house and a self-contained annex. After completion, renovation works continued. Those works included replacing external features such as a patio and fencing, and there was discussion about reinstating or adding fencing around the annex entrance to create a small private garden area for the annex occupier.

The buyer wanted to know whether those later works would support the argument that the annex was a separate dwelling, or whether they might count against the claim. There was also a concern about whether the wording in paragraph 7(2)(a) of Schedule 6B, dealing with a dwelling that is “in the process of being constructed or adapted for such use”, could assist.

Nick’s Explanation

Nick’s core view was that the key legal question was not whether later cosmetic or boundary works could improve the position after the event, but whether the annex was already a separate dwelling at the effective date and whether any later works reduced the number of dwellings.

His reasoning can be summarised like this:

• If the annex already had the physical characteristics of a separate dwelling at completion, later fencing or privacy works are not usually what determines the SDLT outcome.
• Necessary repair works do not automatically merge two dwellings into one, especially where the works preserve safety or structural integrity rather than change the essential use of the accommodation.
• A lockable internal or connecting door may support separation rather than undermine it, depending on the facts, because a secure door can preserve privacy and security between two units.
• The real legal test is whether there has been a reduction in the number of dwellings. If the annex still has its own entrance, kitchen, bathroom and the practical ability to function as a single dwelling, the argument remains that no disqualifying event has occurred.

In anonymised form, Nick’s position was that a later safety-driven installation of a lockable fire-rated door was “a barrier” which increased privacy and security between the two parts of the property, rather than an alteration that turned two dwellings into one.

The Law

MDR was governed by Schedule 6B to the Finance Act 2003 for relevant transactions before its abolition for most new claims. Where it applied, relief could be available if a purchaser acquired an interest in at least two dwellings in a single transaction or linked transactions.

The starting point is the definition of a “dwelling” in section 116 Finance Act 2003. Broadly, a building or part of a building counts as a dwelling if it is used or suitable for use as a single dwelling, or is in the process of being constructed or adapted for such use.

For annex cases, the issue is usually whether the subsidiary accommodation was, at the effective date of the transaction, objectively suitable for use as a single dwelling. This is a factual question. Tribunals and courts look at matters such as:

• separate access
• kitchen and bathroom facilities
• sleeping and living accommodation
• privacy and security
• the degree of physical and functional separation

Where MDR has been claimed, Schedule 6B also contains rules about “disqualifying events”. In broad terms, if within the relevant period an event occurs which means the number of dwellings is reduced, relief can be withdrawn or clawed back.

The phrase in paragraph 7(2)(a) about a building being “in the process of being constructed or adapted for such use” can sometimes help where works are underway at the effective date. But it is not a general cure for weak facts. The question remains whether, viewed objectively, the building or part-building was in the relevant state at the effective date.

Where arguments are made that a property was uninhabitable or not suitable for use as a dwelling, readers should note that the threshold is now relatively high following Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799. Minor defects, disrepair, or the need for improvement works will not usually be enough.

Analysis

In a house-and-annex case, the analysis should be carried out in stages.

1. Identify the effective date of the transaction.

   The condition and layout of the property on that date is critical. Later improvements may provide evidence of the intended use, but they do not rewrite the facts at completion.

2. Ask whether the annex was suitable for use as a single dwelling at that date.

   This is an objective test. An annex with its own entrance, kitchen, bathroom and living space may qualify even if it shares some wider site features with the main house. Shared council tax treatment, a shared garden, or practical links between the units are relevant but not conclusive.

3. Consider whether later works merely improved privacy or repaired defects.

   Replacing fencing or creating a small private garden area may support the factual picture of separate occupation, but if these works happened after completion they are usually not decisive. They are more likely to be evidential background than the legal basis of the claim.

4. Consider whether any later work reduced the number of dwellings.

   This is where HMRC may argue that a disqualifying event occurred. But a repair that preserves structural safety, or the installation of a lockable door that maintains security between the units, does not necessarily reduce the number of dwellings. The substance matters more than the label attached to the work.

5. Be careful with the “constructed or adapted” wording.

   Paragraph 7(2)(a) may help if, at the effective date, the annex was already in the process of being adapted for use as a separate dwelling. However, trying to rely on later works carried out well after completion is more difficult. The provision is not designed to let a purchaser create the necessary dwelling only after the tax point has passed.

On these facts, later fencing around the annex entrance is unlikely by itself to decide the MDR issue either way. It may help demonstrate intended privacy and separate occupation, but the stronger points are likely to be the annex’s existing facilities and whether the later works changed the number of dwellings.

If HMRC argues that a connecting door or similar work was a disqualifying event, the response is to focus on function and effect. A lockable, fire-rated door installed for structural and fire-safety reasons may strengthen separation rather than remove it. That is very different from opening up the property so that the annex loses practical independence.

Any reliance on Fiander and Brower needs careful handling. The significance of a connection between two parts of a building depends heavily on whether the arrangement preserves privacy, security and practical independence, or whether it creates one integrated dwelling.

Outcome

The practical conclusion is that later fencing, patio replacement, or similar external works will rarely be the main factor in deciding whether MDR was available for an annex. The main question is whether there were two dwellings at the effective date of purchase.

If later works did not reduce the annex’s independence, and especially if a later door was a necessary repair that maintained a secure barrier between the units, there is a reasonable argument that no disqualifying event occurred. But later works cannot usually be relied on to create a second dwelling retrospectively if the annex was not already suitable for use as a single dwelling at completion.

Practical Steps

• Gather evidence showing the annex layout and facilities at the effective date, including plans, survey material, photos and completion documents.
• Identify which works were done before completion and which were done afterwards.
• Separate repair works from alterations that changed the way the accommodation functioned.
• Record why any door, fencing or structural work was carried out, especially if it was required for safety, structural integrity or fire compliance.
• Check whether the annex retained its own entrance, kitchen, bathroom and practical ability to be occupied independently after the works.
• If HMRC alleges a disqualifying event, focus on whether the number of dwellings was actually reduced.
• Do not assume that “not suitable for use” arguments will be easy to run; after Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799, the threshold is relatively high.

Conclusion

For MDR annex cases, later privacy or repair works usually matter less than the condition and layout at completion. The key issues are whether the annex was objectively suitable for use as a single dwelling on the effective date, and whether any later event genuinely reduced the number of dwellings. A later lockable safety door or fencing does not automatically defeat the claim, and may on the facts support continued separation rather than merger.

Legal References Used

• Finance Act 2003, section 116
• Finance Act 2003, Schedule 6B
• Finance Act 2003, Schedule 6B, paragraph 7(2)(a)
• Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799
• Fiander and Brower

This page was last updated on 22 March 2026.

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