Stamp Duty Land Tax Adjustments: Land Transaction Return Requirements and Repayment Claims

SDLT adjustments where the purchase price is not fixed at the start

If part of the price for land is contingent, uncertain or not yet known when the transaction completes, the SDLT position may need to be updated later. If a later event means more SDLT is due, the buyer must file a further land transaction return within 30 days, using the SDLT rates that applied on the original effective date. If too much SDLT was paid, a repayment claim may be made and HMRC says interest may be payable on the overpaid amount.

• This applies where the consideration was not fully fixed when the land transaction first became effective.
• If the contingency ends or the amount later becomes ascertainable, the SDLT calculation may need to be revised under Finance Act 2003, section 80.
• Where the later event increases the chargeable consideration, a further land transaction return with a fresh self-assessment must be filed within 30 days, and any extra tax must be paid.
• The SDLT must be recalculated using the rates and thresholds in force on the original effective date, not those applying when the later event happens.
• If the later event shows that too much SDLT was paid, a repayment claim may be available, with interest running from the date of payment.
• In practice, the main risks are spotting when the 30-day deadline starts and monitoring later trigger events, especially where payment was previously deferred or the contract terms are complex.

Scroll down for the full analysis.

SDLT adjustments for contingent, uncertain or unascertained consideration: when a further return is needed

This page explains what happens if the price for land is not fully fixed when the transaction first takes place, and later becomes known or changes. In those cases, the SDLT position may need to be adjusted. The key practical point from the official source is that, if more tax becomes due, a further land transaction return must be filed within 30 days of the relevant event.

What this rule is about

Some land transactions do not have a final, settled amount of consideration on day one. The amount payable may depend on a future event, may be uncertain, or may not yet be capable of being worked out. SDLT still has to be dealt with, even though the price is not fully fixed.

The source material deals with what happens later, when that uncertainty ends or the amount becomes ascertainable. At that point, the original SDLT calculation may need to be revisited under Finance Act 2003, section 80.

This matters because SDLT is not always a one-and-done filing exercise. In transactions with deferred or variable consideration, there can be a later compliance step, and missing it can lead to underpaid tax remaining unpaid after the statutory deadline.

What the official source says

HMRC’s manual says that where the SDLT payable needs to be adjusted because a contingency has ceased or consideration has become ascertained, a land transaction return is required within 30 days of that event.

That further return must include a self-assessment of the SDLT payable. The tax must be calculated using the rates that applied at the effective date of the original transaction, not rates in force at the later adjustment date. Any additional tax due must be paid with the return.

The manual also states that if the later event means that less SDLT is due, a repayment claim can be made. HMRC says interest will be paid on the overpaid tax from the date the tax was paid.

The source refers to related guidance where tax payment had previously been deferred. That is an administrative point about where the further return should be sent in those cases.

What this means in practice

If a property deal includes a price element that depends on future facts, you cannot assume the original SDLT filing is the end of the matter.

There are two broad possibilities:

• the later event shows that more consideration is payable, so more SDLT is due
• the later event shows that less consideration is payable, so too much SDLT was originally paid

Where more SDLT is due, the buyer must file a further land transaction return within 30 days of the contingency ending or the amount becoming ascertainable. The return is not simply an update. It must contain a fresh self-assessment of the tax due by reference to the original effective date rates.

Where less SDLT is due, the source says a repayment claim can be made. The official material here does not set out the detailed mechanics of that claim, but it makes clear that overpaid tax can be recovered and that interest is payable from the date of payment.

The reference to the rates in force at the effective date is important. It means you do not recalculate by using whatever SDLT thresholds or rates happen to apply when the uncertainty is resolved. You look back to the original transaction date for the rate structure.

How to analyse it

A sensible way to approach this issue is to ask the following questions:

• Was any part of the consideration contingent, uncertain, or unascertained when the transaction became effective?
• Has the relevant contingency now ceased, or has the amount now become ascertainable?
• Does the later event increase the amount of chargeable consideration, or reduce it?
• If it increases the consideration, has a further land transaction return been prepared and filed within 30 days?
• Has the SDLT been recalculated using the rates that applied at the original effective date?
• If the later event reduces the tax due, is a repayment claim available on the facts?
• Was any deferment of tax previously granted, and if so, are the correct HMRC administrative steps being followed?

For conveyancers and advisers, the practical challenge is often diary management. The later triggering event may happen months or years after completion. If no one monitors it, the buyer may miss the 30-day deadline for the further return.

Example

Suppose a buyer acquires land for a fixed sum plus an additional amount that will only become payable if planning permission is granted. At the effective date of the transaction, the additional amount is contingent.

Two years later, planning permission is granted and the amount of the additional payment becomes known. If that means more SDLT is due overall, the buyer must file a further land transaction return within 30 days of the contingency ceasing or the consideration becoming ascertainable. The SDLT is worked out using the rates that applied on the original effective date of the purchase, not the rates in force two years later.

If, instead, the later event shows that the buyer has overpaid SDLT, the source indicates that a repayment claim can be made, with interest on the overpaid amount from the date it was paid.

Why this can be difficult in practice

The main difficulty is identifying exactly when the 30-day clock starts. The source uses two triggers: when the contingency ceases, or when the consideration is ascertained. In straightforward cases those dates may be obvious. In more complex commercial arrangements, they may not be the same date, and the documents may need to be read carefully to work out when the amount truly became fixed.

Another practical difficulty is distinguishing between a genuine later ascertainment of consideration and a different kind of later event that does not fall within this rule. The source page is short and assumes familiarity with the wider SDLT framework on contingent, uncertain and unascertained consideration.

There can also be administrative risk where tax was previously deferred. The source flags that special handling may be needed in those cases.

Finally, readers should not confuse HMRC’s manual with the legislation itself. The manual explains HMRC’s view of how the statutory adjustment process operates, but the legal obligation ultimately depends on the legislation, including Finance Act 2003 section 80 and the wider rules on chargeable consideration.

Key takeaways

• If later events change or fix the amount of consideration, the SDLT position may need to be adjusted.
• Where more SDLT becomes due, a further land transaction return must be filed within 30 days of the relevant event.
• The recalculation uses the SDLT rates in force at the original effective date, and overpaid tax may be reclaimable with interest.

This page was last updated on 24 March 2026

Useful article? You may find it helpful to read the original guidance here: Stamp Duty Land Tax Adjustments: Land Transaction Return Requirements and Repayment Claims

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