Married vs unmarried couples: second-home stamp duty in 2026

Two couples buy the same £295,000 house — the median-priced home in England, based on 737,746 HM Land Registry transactions recorded in 2025. In each couple, one partner already owns a flat elsewhere; the other owns nothing. One couple is married, the other is not. Depending on how they buy, the married couple can pay £19,500 in Stamp Duty Land Tax (SDLT) where the unmarried couple pays £4,750 — a difference of £14,750 on an identical purchase.

The gap comes entirely from one rule inside the additional-property surcharge — a rule that makes marital status part of the tax test. Here is how it works, and the single situation where it flips.

The two rate columns

England and Northern Ireland charge SDLT on residential property at two sets of rates. The standard rates start at 0% below £125,000 and rise in slabs. Since 31 October 2024, a buyer of an additional dwelling pays a surcharge of 5 percentage points on top of every band (HMRC). Because that extra 5% bites from the first pound, the surcharge is always exactly 5% of the purchase price:

Figures from the Homecost stamp duty calculator, England, July 2026.

Whether a buyer lands in the left column or the right depends on the additional-property test in Schedule 4ZA of the Finance Act 2003 — and that is where marriage matters.

The surcharge test, in plain terms

The surcharge applies to an individual buyer when, broadly, all of these are true (FA 2003, Schedule 4ZA, paragraph 3):

• the price is £40,000 or more;
• at the end of the day of the purchase, the buyer holds a major interest worth £40,000 or more in another dwelling; and
• the new home is not replacing the buyer's only or main residence.

Own no other property and you never pay the surcharge. Own a second dwelling and buy without selling your main home, and it generally applies. The question for couples is whose property counts.

Rule one — the spouse-attribution rule (buying in a sole name)

Paragraph 9 of Schedule 4ZA treats a married couple or civil partners who are living together as a single unit. For the additional-property test, a dwelling owned by one spouse is treated as if it were also owned by the other. Living together here is a legal status, not a shared address: a couple counts as living together unless they are separated under a court order, under a deed of separation, or in circumstances likely to be permanent — a definition drawn from section 1011 of the Income Tax Act 2007.

The practical effect: if one spouse buys a home in their sole name and the other spouse owns a separate flat, that flat is attributed to the buyer. The purchase is charged at the higher rates even though the person on the title owns nothing else.

Unmarried cohabitees are not aggregated. Two people who genuinely share a home but are not married or in a civil partnership are each tested only on the property they personally hold. So if one unmarried partner buys in their sole name, the other partner's flat is invisible to the surcharge test.

That is the £14,750 swing at the median: on a sole-name purchase, marriage pulls the partner's property into the calculation; cohabitation does not.

Rule two — the "one bad apple" rule (buying jointly)

Buy jointly, and marriage stops being the deciding factor. Where a transaction has two or more purchasers, Schedule 4ZA applies the test to each of them, and if it is met for any one buyer, the whole purchase is charged at the higher rates. HMRC's guidance puts it plainly: if any joint buyer already owns another property, the surcharge applies to the entire transaction (gov.uk).

So an unmarried couple buying together, where just one of them owns a flat, pays the surcharge on the whole £295,000 — the same result a married couple gets. The joint-buyer stamp duty trap catches married and unmarried buyers alike.

The four cases side by side

Take the couple buying a £295,000 home to live in, where one partner already owns a separate flat and they are not selling a home they both live in:

Only one cell differs: the sole-name purchase. Everywhere else, owning an additional dwelling between them produces the surcharge regardless of marital status. And if neither partner owns any other property, all four cells collapse to the standard £4,750 — the surcharge is about second dwellings, not relationships.

The exception that resets everything

One large caveat runs underneath the whole table: replacement of a main residence. If the couple are selling the home they currently live in and buying this one to replace it, the new purchase replaces their only or main residence — the third condition above is not met — and the surcharge does not apply, even where one of them owns an additional property elsewhere (FA 2003, Schedule 4ZA, paragraph 3).

Where a previous main home is sold after the new one is bought, the surcharge is paid up front and can be reclaimed if the old home sells within the statutory window, through the additional-property surcharge refund route. The mechanics — and the deadlines — are strict.

First-time buyers pay a different tax altogether

None of this touches a genuine first-time buyer. A first-time buyer purchasing the same £295,000 home pays £0, because the price falls under the £300,000 first-time-buyer nil-rate threshold (HMRC, July 2026). First-time buyer relief is a separate test with its own conditions, and it is withdrawn once a buyer has ever held a major interest in a dwelling anywhere in the world.

To see the all-in monthly cost of a specific home — mortgage at the current Bank of England quoted rate, plus council tax and energy on top of the one-off SDLT — enter a postcode such as M1 1AE on Homecost, or work the figures through on the stamp duty calculator. More explainers are collected under Cost Intelligence.

Based on 737,746 HM Land Registry Price Paid transactions for 2025 and the SDLT rates in force in July 2026 (browse all guides). This is general information about how the rules work, not tax advice, and individual circumstances change the answer. Speak to a qualified adviser before acting.