Transfer of equity and the £40,000 stamp duty return trap

Adding a partner to the deeds, or taking an ex-partner off them, rarely produces a stamp duty bill. But it can still produce a legal obligation: the duty to file a return with HM Revenue & Customs. The line that decides it is a single figure written into the Finance Act 2003 and unchanged since — £40,000.

A transfer of equity — changing who legally owns a property without a full open-market sale — is a "land transaction" for Stamp Duty Land Tax (SDLT). What matters is not the property's value but the chargeable consideration: the cash the incoming owner pays, plus the share of any outstanding mortgage they take on (Finance Act 2003, Schedule 4, paragraph 8). Taking on a slice of a mortgage counts as giving something, even when no cash changes hands. How that consideration is charged is covered in our guide to how stamp duty applies to a transfer of equity; this piece looks only at the narrower question that trips people up afterwards — do you have to tell HMRC at all?

The £40,000 line: return due, tax often nil

For a freehold acquisition (or most other non-lease transfers), a land transaction is notifiable — meaning a return must be delivered — once the chargeable consideration reaches £40,000 (Finance Act 2003, section 77A). Below £40,000 there is generally no return and no tax. At or above it, a return is usually required — even where the tax itself computes to zero.

That creates a band where the paperwork is due but the bill is not. The standard nil-rate band is £125,000, so any consideration between £40,000 and £125,000 lands squarely in it (figures below confirmed via Homecost's SDLT calculator, 9 July 2026):

The £40,000-to-£125,000 stretch is the dead band: HMRC expects a return, but the calculation lands at nil. It is exactly where a great many transfers of equity sit.

The same £40,000 line does a second job

For anyone who will still own another dwelling after the transfer — the additional-property, or "higher rates", position — the £40,000 figure does double duty. The higher rates apply only where the chargeable consideration is £40,000 or more (Finance Act 2003, Schedule 4ZA, paragraph 3(2)). So below £40,000 there is neither a surcharge nor a return. At or above it, the 5% surcharge applies to the whole consideration and a return falls due:

• A £30,000 share taken on by someone who owns no other property: £0, and no return.
• A £50,000 share where the higher rates apply: £2,500 (5% of £50,000), and a return is due.
• A £125,000 share where the higher rates apply: £6,250, and a return is due.

The additional-property surcharge is a flat 5% of the consideration from the first pound above the £40,000 line — so on a transfer of equity it can turn a nil-tax event into a four-figure one. The £125,000 standard nil-rate band itself is a recent number: it dropped from £250,000 on 1 April 2025, as set out in our summary of what changed in the April 2025 stamp duty rules.

Why the line bites on transfers of equity specifically

On a full open-market purchase, the £40,000 threshold is almost irrelevant. Of the 699,846 full-market residential sales recorded across England during 2025, just 0.12% (831 sales) completed under £40,000, and only 7.16% at or below the £125,000 nil-rate band (HM Land Registry Price Paid Data, fetched 9 July 2026). The median sale was £300,000.

A transfer of equity is different because it is charged on a share, not the whole. But the share is usually a share of the mortgage debt, and mortgage balances are large. Half of a £150,000 outstanding mortgage is £75,000; half of the debt on a median-priced home is comfortably into six figures. So the very transactions that produce no tax — a partner joining a mortgaged home, a buyout under the nil-rate band — are the ones most likely to cross £40,000 and become notifiable. The 0.12% figure that makes the threshold trivial on a full purchase does not protect a transfer of a mortgaged half-share.

The penalty for a missed return

An SDLT return, where one is required, must reach HMRC within 14 days of the effective date of the transaction — normally completion (Finance Act 2003, section 76). The 14-day window has applied since 1 March 2019.

Miss it, and a flat penalty applies regardless of whether any tax was due: £100 if the return is delivered within three months of the filing date, and £200 if it is later (Finance Act 2003, Schedule 10, paragraph 3). A further tax-related penalty can follow if a return is more than twelve months late, but for a nil transfer that element is £0 — leaving the fixed £100 or £200 as the real exposure. It is a small sum, but it attaches to precisely the transfers people assume they can ignore because "there's no stamp duty to pay".

Check the number, not the assumption

The safest habit is to work out the chargeable consideration first — cash plus the share of debt assumed — and only then ask whether it clears £40,000. You can model the tax side for any figure with Homecost's stamp duty calculator, and see the full monthly cost picture behind a move by searching a postcode, for example B1 1AA in central Birmingham.

This is general information about how the rules work, not advice on your own transaction. A conveyancer confirms whether a return is notifiable and files it on completion. Speak to a qualified adviser before acting.