Understanding SDLT Higher Rate for Non-Natural Persons: ‘Significant Part of the Interior

When public access to part of a dwelling counts as a significant interior area for SDLT

For SDLT higher-rate rules affecting companies and other non-natural persons buying residential property, a dwelling may fall outside the charge if it is genuinely used in a qualifying trade. Where the public is admitted, HMRC looks at whether a significant part of the inside of the dwelling is open to them. This depends on both the size of the area and how important that area is to the property and the trade, so small but key rooms may qualify, while minor or incidental access usually will not.

• The whole dwelling does not need to be open to the public, but the part that is open must be significant.
• HMRC judges significance by looking at both the proportion of the interior made available and the nature and function of the rooms involved.
• A small number of important rooms, such as principal rooms in a historic house, may still count as a significant part of the interior.
• Access to minor areas such as lobbies, ticket points or toilets is unlikely to be enough if the main attraction is outside, for example in the gardens.
• There is no fixed percentage test, so each case depends on the facts and on whether the interior is a real and meaningful part of the trading activity.

Scroll down for the full analysis.

When part of a dwelling is open to the public: what counts as a “significant part of the interior” for SDLT

This page explains a narrow but important SDLT point. It concerns the higher rate charge for certain non-natural persons acquiring residential property, and in particular when a dwelling may fall outside that charge because it is used in a qualifying trade. The specific issue here is what HMRC means by a “significant part of the interior” being made available to the public.

What this rule is about

Some SDLT rules impose a higher rate of tax when certain companies and other non-natural persons acquire residential property. There are exceptions and reliefs where the dwelling is genuinely being used in a property-related trade or another qualifying business activity. One situation considered by HMRC is where the property is used in a trade that involves admitting the public.

In that context, it is not enough to ask whether any part of the building is open to visitors. The question is whether a significant part of the inside of the dwelling is made available to the public. This matters because token or incidental access will not usually be enough.

What the official source says

HMRC’s manual says that the whole dwelling does not need to be used in the trade. A property can still meet the test even if only part of it is opened to the public.

However, the part that is opened must be significant. HMRC says significance is judged by looking at:

• the size of the area made available to the public compared with the size of the dwelling as a whole, and
• the nature and function of the part that is opened.

So the test is not purely about floor area or number of rooms. A minority of the rooms may still be enough if those rooms are important in the context of that particular property.

HMRC gives the example of a stately home. Even if the main state rooms are less than half the total floor area and less than half the total number of rooms, they may still be a significant part of the interior because of their importance and function within the house.

By contrast, if the public mainly visit the gardens and are only allowed into a small or unimportant internal area, such as toilets, that will not be enough to take the dwelling out of charge.

What this means in practice

The practical point is that public access must be real and meaningful. The rule is aimed at properties where part of the dwelling is genuinely part of the trading activity, not where public entry inside the house is trivial or merely supportive of an outdoor attraction.

This means you should not focus only on measurements. A room can be significant because of what it is, not just because of how large it is. In a historic house, formal reception rooms may be the main attraction. Opening those rooms to visitors may carry more weight than opening a larger amount of less important space.

On the other hand, limited internal access that exists only so visitors can pass through, buy tickets, or use facilities is unlikely to satisfy the test if the real attraction is elsewhere.

The source material is from HMRC’s manual. That is HMRC’s view of how the legislation applies. In practice, conveyancers and advisers would use it to assess risk and likely HMRC treatment, but the legal outcome ultimately depends on the legislation applied to the facts.

How to analyse it

A sensible way to approach this issue is to ask the following questions:

• What part of the dwelling is actually open to the public?
• Is that internal access a real part of the trade, or only incidental?
• How large is the accessible area compared with the dwelling as a whole?
• Are the rooms opened to the public important rooms in the context of that property?
• What is the public being admitted to see or use?
• Is the interior itself part of the attraction, or is the attraction mainly outside the dwelling?

When applying those questions, both size and importance matter. Neither is decisive on its own. A relatively small area may still be significant if it represents the key historic, architectural, or functional part of the house. Equally, a physically accessible area may still fail if it is minor and unimportant.

Example

Illustration: A company buys a large historic house. Visitors are admitted to four principal reception rooms used for public tours, but the rest of the house remains private. Those four rooms make up less than half of the total floor area. Even so, if they are the main ceremonial and historic rooms that define the character of the property, HMRC’s approach suggests they may amount to a significant part of the interior.

By contrast, if visitors come mainly to see the grounds and are allowed only into a small lobby and toilet area inside the house, that would not usually be enough. The interior access would be too minor in size, nature, and function.

Why this can be difficult in practice

The phrase “significant part of the interior” is inherently fact-sensitive. There is no mechanical percentage test in the source material. That creates uncertainty in borderline cases.

Difficulties often arise where:

• the accessible rooms are few in number but highly important;
• the public enters the dwelling for mixed reasons, partly to view it and partly for facilities or circulation;
• the property is very large, so even major rooms represent a small proportion of total floor area;
• the trade centres on the estate as a whole, rather than clearly on the interior of the dwelling.

In those cases, the analysis turns on the actual character of the public use. The more the interior itself is a meaningful part of what is being commercially offered to the public, the stronger the argument that a significant part of the interior is being exploited in the trade.

Key takeaways

• The whole dwelling does not need to be used in the trade for this test to be met.
• “Significant” depends on both the size of the area opened to the public and its nature and function within the dwelling.
• Minor or incidental internal access, such as entry only to reach toilets while visiting gardens, will not usually be enough.

This page was last updated on 24 March 2026

Useful article? You may find it helpful to read the original guidance here: Understanding SDLT Higher Rate for Non-Natural Persons: ‘Significant Part of the Interior

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