SDLT Higher Rates for Unmarried Couples Buying Together When Each Already Owns Property
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Do unmarried couples pay higher SDLT when buying a new home if each already owns property?
Introduction
This question often comes up where an unmarried couple want to buy a new home together, but each already owns one or more properties. The key SDLT issue is whether the new purchase counts as a replacement of an only or main residence. If it does, the normal residential rates may apply. If it does not, the higher rates for additional dwellings may apply.
The difficulty is that SDLT looks closely at what each buyer owns at the end of the day of completion, and whether each buyer is replacing a previous main residence. That is why people can receive conflicting advice, especially where one property has been moved onto a buy-to-let mortgage or has been rented out after the owner moved elsewhere.
The Question
An unmarried couple plan to buy a new home together as their main residence. One partner owns:
- a rental property acquired by inheritance, which will be kept, and
- a property that has been used as that partner’s home, which is intended to be sold.
The other partner owns a property that was originally bought as their home, but they later moved in with their partner and began letting that property out. That property is also intended to be sold.
The couple want to know whether the purchase of the new shared home will be charged at the normal residential SDLT rates or the higher rates for additional dwellings.
Nick’s Explanation
Nick’s explanation was that the answer turns on Schedule 4ZA to the Finance Act 2003. In summary, the higher rates apply if, at the end of the day of purchase, a buyer still owns another dwelling and is not replacing their only or main residence.
He explained the position in substance as follows:
“To be classed as a replacement of a main residence, the previous home must have been the buyer’s only or main residence and must have been disposed of before or on the same day as completion of the new purchase.”
He also noted that if either relevant former home is still owned personally at completion, the 5% higher rates can apply. However, where the old main residence is sold within 36 months after the new purchase, a refund claim may be possible.
The important timing point in this kind of case is that a property which used to be someone’s home does not remain their previous main residence indefinitely for refund purposes. If too much time passes after moving out, the refund route can be lost.
The Law
SDLT is charged under Part 4 of the Finance Act 2003. The basic charging provisions include:
- section 42, which charges SDLT on land transactions,
- section 43, which refers to the acquisition of a chargeable interest, and
- section 48, which defines chargeable interest.
For residential purchases, the higher rates for additional dwellings are found in Schedule 4ZA to the Finance Act 2003.
Broadly, the higher rates apply where, at the end of the effective date of the transaction, the purchaser owns an interest in another dwelling worth at least the minimum threshold and the new purchase is not a replacement of the purchaser’s only or main residence.
Where there is more than one buyer, the rules are applied in a strict way. If the higher rates apply to any one of the joint purchasers, the higher rates apply to the whole transaction.
A purchase can still qualify as a replacement of a main residence even if the buyer keeps another dwelling, provided the dwelling kept is not the residence being replaced. In other words, keeping a rental property does not automatically trigger the surcharge if the buyer is genuinely replacing their main home and the statutory conditions are met.
If the former main residence is sold after the new purchase, a refund of the higher rates may be available, but only if the statutory conditions and time limits are satisfied. One of the critical conditions is that the sold property must have been the buyer’s only or main residence at some point during the three years ending with the purchase of the new dwelling.
Questions sometimes arise about whether a property was suitable for use as a dwelling. In uninhabitable or not suitable for use cases, the condition thresholds are now relatively high following Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799. That authority makes clear that ordinary disrepair or a need for renovation will often not be enough.
Analysis
The analysis in this scenario can be broken down into four steps.
First, identify what each buyer will own at the end of the day of completion of the new purchase.
If one partner keeps an inherited rental property, that property still counts as another dwelling owned by that buyer. That fact alone does not settle the issue, but it is relevant.
If the property that has served as that partner’s home is sold before or on completion of the new purchase, that buyer may still be treated as replacing their only or main residence, despite keeping the inherited rental property.
Second, identify the other partner’s previous main residence.
If that partner bought a property as their home and later moved out and let it, that property can still potentially count as their previous main residence for replacement purposes. The fact that it is now rented out and on a buy-to-let mortgage does not automatically stop it from being treated as the former main residence. What matters is whether it really was their only or main residence before they moved out, and whether the statutory timing rules are met.
Third, consider whether the old residences are disposed of before or on completion.
If both former homes are sold before or on the same day as the new joint purchase completes, the new purchase is much more likely to fall within the replacement of main residence rules, so that the normal residential rates apply.
If one or both former homes are still owned personally at completion, the higher rates are likely to apply on the day of purchase, because at least one buyer will still own another dwelling and will not yet have completed the replacement conditions.
Fourth, consider whether a refund could later be claimed.
If the higher rates are paid because one former home is sold late, a refund may be available if that former home is sold within 36 months after the new purchase and if it had been that buyer’s only or main residence during the three years ending with the new purchase.
This timing rule is especially important where someone moved out some time ago and has been renting the old property since then. Once the old home falls outside the relevant three-year look-back period, it may no longer qualify as the previous main residence for refund purposes.
In practical terms, this means:
- keeping a separate rental property does not by itself prevent normal rates from applying;
- selling the actual former main residences before or on completion is the safest route if the aim is to avoid the surcharge at the outset;
- if either former home is retained at completion, the higher rates may need to be paid first; and
- a later refund depends on strict residence and timing tests.
The fact that the couple are unmarried is also important. Unmarried buyers are tested individually under Schedule 4ZA. Marriage does not simply make SDLT problems disappear; in some situations spouses are treated as one unit for higher-rates purposes, which can produce different consequences rather than easier ones. The correct SDLT answer always depends on the statutory tests and the exact ownership position at completion.
Outcome
If both former main residences are sold before or on the same day as the purchase of the new shared home, the normal residential SDLT rates should generally apply, even if one partner keeps a separate rental property.
If either former main residence is still owned personally at completion, the higher rates for additional dwellings are likely to apply to the whole purchase.
A refund may then be available if the relevant former main residence is sold within 36 months and the statutory residence conditions are met. But where a buyer moved out of their old home too long ago, the refund route can be lost.
Practical Steps
To assess the SDLT position properly, a buyer should work through the following points:
- List every dwelling each buyer will own at the end of the day of completion.
- Identify which property was each buyer’s actual only or main residence.
- Check whether that former main residence will be sold before, on, or after completion of the new purchase.
- For any property already let out, confirm the date the owner moved out and whether it had genuinely been their home before then.
- Check whether any possible refund claim would still fall within the three-year statutory window.
- Keep evidence of occupation, such as council tax records, electoral roll entries, utility bills, mortgage history and letting dates, in case HMRC later queries whether a property was truly a main residence.
- If there is any suggestion that a property was uninhabitable, test that carefully against the high threshold now indicated by Amarjeet and Tajinder Mudan v The Commissioners for HMRC [2025] EWCA Civ 799.
Conclusion
For unmarried joint buyers, SDLT on a new home depends mainly on whether each buyer is replacing a previous main residence and what each still owns at completion. Selling both former homes before or on completion will usually avoid the higher rates. If that does not happen, the surcharge may apply first, with a refund only if the strict statutory conditions are met in time.
Legal References Used
- Finance Act 2003, Part 4
- Finance Act 2003, section 42
- Finance Act 2003, section 43
- Finance Act 2003, section 48
- Finance Act 2003, Schedule 4ZA
- 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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