HMRC has revised SDLTM85930, its guidance on the relevant date for interest on unpaid SDLT. The opening statement now refers to interest running from 14 days after that date. Solicitors should not turn that statement into a universal diary rule.

The legislation distinguishes between returns and certain further returns. That distinction remains important where a later linked transaction produces additional tax on an earlier acquisition.

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Guidance at a glance

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Source: HMRC SDLTM85930; revision published 1 September 2026.

Status: administrative guidance, not a change to legislation or a court decision.

Issue: the opening 14-day statement does not express the full statutory distinction.

Key point: identify the return type and the relevant date before calculating interest.

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What the legislation says

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Section 87(1) Finance Act 2003 retains a 30-day starting point for interest. Section 87(1A) substitutes 14 days only where its specified conditions are met, including that a return is required within 14 days of the relevant date. The 30-day rule is therefore not merely a historical rule for pre-March 2019 transactions.

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This is also consistent with HMRC’s explanation of the 2019 reforms: the shorter deadline did not displace the 30-day deadline for further returns.

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Later linked transactions: the practical distinction

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The changes enacted by section 46(5) Finance Act 2019 distinguish two outcomes under section 81A. If the earlier transaction becomes notifiable, a return is required within 14 days of the later transaction. If the earlier transaction was already notifiable and the later transaction creates tax, or additional tax, a further return is required within 30 days. Payment is tied to that filing date.

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HMRC’s existing SDLTM50350 describes the same practical distinction. A later purchase may therefore require its own ordinary return on a 14-day timetable while generating a 30-day further-return obligation for the earlier purchase. A single completion date need not mean a single deadline.

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Why the wording matters

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Our analysis is that the revised opening sentence is overbroad when read as applying to every case listed on the page. This is a technical qualification, not a suggestion that ordinary SDLT returns generally have a 30-day deadline. The applicable statute takes priority over a manual summary.

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Nor should the linked-transaction example be used as a shortcut for all later liabilities. Relief withdrawals, leases and deferred consideration require their own statutory analysis. The relevant date and the length of the interest-free period are separate questions.

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Changes to precedents and risk controls

• Record separately: statutory trigger, return or further return, filing deadline, payment deadline and interest start date.
• Retain the original return, later transaction documents and dated calculation supporting any additional liability.
• Add a 14/30-day distinction to linked-transaction training. Do not replace all further-return deadlines with 14 days.
• Check an HMRC interest calculation against the statute before accepting it; preserve the guidance version relied on.

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This is commentary on published guidance and legislation as at 1 September 2026. No judicial ruling or appeal arises from the update, and no HMRC correction of this wording has been identified. Transaction-specific advice remains necessary.