How long do you need to live in a property for it to count as your main residence for SDLT?

Introduction

A common Stamp Duty Land Tax question is whether moving into a partner’s home for a period of time can make that property your “only or main residence” so that a later purchase qualifies as a replacement of main residence and avoids the higher rates for additional dwellings.

This issue matters most where one buyer owns a difficult-to-sell flat or house and the couple want to buy a new home together. The key point is that SDLT does not set a fixed minimum period such as 6 months, 12 months or 18 months. The legal test is factual. HMRC and the legislation look at whether the property was genuinely the person’s only or main residence, not whether they crossed a set time threshold.

The Question

An unmarried couple each own a separate property. One partner owns and lives in a house that is expected to be sold. The other owns a flat that was previously their long-term home, but it has become very hard to sell because of building-related issues and lender reluctance.

They want to buy a new home together. Their concern is that if one of them still owns the flat at the time of purchase, the higher SDLT rates for additional dwellings may apply to the whole transaction. They therefore want to know:

• whether moving into the other partner’s house for a period would make that house their main residence for SDLT purposes;
• how long they would need to live there;
• whether marriage changes the SDLT result; and
• whether there is any exception because the flat is hard to sell or arguably unsuitable.

Nick’s Explanation

Nick’s key point was that there is no statutory minimum period of occupation for SDLT main residence purposes. As he put it in substance, “the test is factual, not time-based, and hinges on intention and actual occupation.”

He also explained that if the house is genuinely the other partner’s main residence, and that partner is given a share before the house is sold, then both buyers may be able to say they have disposed of a main residence. If the next property is then bought as their intended new shared main residence, the replacement of main residence exception may prevent the higher rates from applying.

Nick also noted two wider points:

• if a couple are married or in a civil partnership and living together, SDLT generally treats them as one unit for higher-rates purposes; and
• if there are two purchasers, the higher rates can apply to the whole purchase if the conditions are met for either of them, unless the replacement of main residence exception applies.

The Law

The higher rates of SDLT for additional dwellings are contained in Schedule 4ZA to the Finance Act 2003.

The main provisions relevant here are:

• paragraph 2, which sets out when a transaction is a higher rates transaction;
• paragraph 2(3), which deals with joint purchasers and can cause the higher rates to apply to the whole purchase if the conditions are met in relation to any one purchaser;
• paragraph 3, which provides the replacement of only or main residence exception; and
• paragraph 3(7), which contains the timing rule, including the 3-year window for disposal of a previous main residence.

In simple terms, the higher rates may not apply if, on buying the new dwelling, the buyer is replacing a dwelling that has been their only or main residence.

The legislation does not impose a fixed minimum period of residence. Instead, whether a dwelling is a person’s only or main residence depends on the facts. Actual occupation, intention, the quality of occupation, and the surrounding evidence all matter.

Marriage also matters. Spouses and civil partners living together are generally treated together for these rules. That means one spouse’s retained property can affect the SDLT position of the other.

As for a property said to be uninhabitable or unsuitable for use, readers should be aware that the threshold is now relatively high following Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799. A property being difficult to mortgage, expensive to repair, affected by cladding, or commercially unattractive will not necessarily take it outside the SDLT residential rules.

Analysis

The analysis usually has to be done in stages.

First, ask whether the buyer who still owns the flat will own a major interest in another dwelling at the effective date of the new purchase. If yes, that points towards the higher rates applying.

Second, ask whether the purchase can still qualify as a replacement of only or main residence under Schedule 4ZA paragraph 3. This is where the main residence question becomes critical.

Third, if the buyers are purchasing jointly, ask whether the exception applies for the transaction as a whole. Under paragraph 2(3), if the higher-rates conditions are met for one buyer, the whole transaction can be caught unless the replacement exception applies.

Fourth, consider marital status. If the couple are unmarried at the time of purchase, the analysis is done on the statutory rules for joint purchasers without the added spouse aggregation rules. If they are married and living together, one spouse’s retained dwelling is generally attributed across the couple for these purposes.

Fifth, consider whether the person who owns the flat can genuinely establish the other property as their only or main residence before sale and onward purchase. There is no magic number of months. HMRC would look at the whole picture, including matters such as:

• where the person actually sleeps and lives day to day;
• where personal belongings are kept;
• where post is sent;
• bank, driving licence, insurance and electoral records;
• utility and council tax arrangements;
• whether the old property is still occupied by them or has clearly ceased to be their home;
• the parties’ intention at the time of occupation; and
• whether the occupation has the quality of a real home rather than a temporary paper arrangement.

That means 6 months is not automatically enough, but it could be enough on strong facts. Equally, 12 months is not automatically enough if the move was not genuine. The question is substance over form.

Nick’s suggested route involved a further step: if the house owner gives the other partner a share in the house before the sale, and both then sell it, both may have disposed of an interest in a dwelling that was their main residence. If the next property is intended to be their new main residence, paragraph 3(7) may allow the replacement exception to apply.

That route needs careful handling. The transfer of a share must be real and legally effective. It can also have wider tax and conveyancing consequences, especially if there is mortgage debt, beneficial ownership issues, or later marriage planning. The timing of the gift, sale and onward purchase matters.

On the separate idea that HMRC might make an exception because the retained flat is hard to sell, the legislation does not generally work by discretion. HMRC cannot simply waive the surcharge because the facts seem unfair. The result depends on whether the statutory conditions are met.

On the idea that the flat might be ignored because it is unsafe, unmortgageable or hard to use, that argument is now difficult. Following Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799, the threshold for saying a dwelling is not suitable for use as a dwelling is relatively high. Serious practical defects do not automatically remove a property from the SDLT residential regime.

Outcome

The practical answer is that there is no fixed legal minimum period that someone must live in a property for it to count as their only or main residence for SDLT. The test is factual.

If a person genuinely moves into their partner’s house and it becomes their real home, that house can in principle become their only or main residence even without a long period of occupation. If they are then given a genuine share in that property and both dispose of it before buying the next home, the replacement of main residence rules may prevent the 5% higher rates surcharge from applying.

But this is highly fact-sensitive. Paper changes alone are not enough. And marriage can make the SDLT position stricter because spouses living together are generally treated as one unit.

Practical Steps

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

• map out the proposed timeline for any transfer of equity, sale of the current home and purchase of the new home;
• check whether the person moving in can show genuine occupation and intention, not just administrative changes;
• gather evidence of real residence, such as address changes across financial, insurance and official records, movement of possessions, and day-to-day living arrangements;
• review whether the old property has in substance ceased to be that person’s home;
• take advice before any gift of a share in the property, especially where there is a mortgage or unequal contributions;
• consider carefully whether buying before or after marriage changes the SDLT analysis; and
• do not assume that a difficult-to-sell or defective flat falls outside the SDLT dwelling rules, particularly after Mudan.

Conclusion

For SDLT, there is no rule saying you must live in a property for 6, 12 or 18 months before it becomes your main residence. What matters is whether, on the facts, it truly became your only or main residence. If it did, and the disposal and onward purchase are structured within Schedule 4ZA, the replacement of main residence exception may avoid the higher rates. The detail and timing are crucial.

Legal References Used

• Finance Act 2003, Schedule 4ZA
• Finance Act 2003, Schedule 4ZA, paragraph 2
• Finance Act 2003, Schedule 4ZA, paragraph 2(3)
• Finance Act 2003, Schedule 4ZA, paragraph 3
• Finance Act 2003, Schedule 4ZA, paragraph 3(5)–(7)
• 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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