Understanding SDLT: Contract and Conveyance Notification and Tax Obligations Explained

SDLT on Substantially Performed Contracts Later Completed by Conveyance

If a land contract is treated as substantially performed before legal completion, SDLT can arise at that earlier stage. When the transaction is later completed by a conveyance, such as a transfer, that completion must also be notified to HMRC. Any SDLT due on completion is limited to the amount by which the tax on completion exceeds the tax already due on the earlier contract, helping to avoid double charging.

• SDLT can apply before formal completion if the buyer takes possession or another substantial performance trigger occurs.
• If the contract is later completed by conveyance, the later completion is still separately notifiable.
• You compare the SDLT due when the contract was substantially performed with the SDLT due on completion.
• Only the extra amount is payable on completion if the SDLT due then is higher than the amount already charged.
• Even if no further SDLT is payable on completion, the completion must still be notified to HMRC.
• The rules can be fact-sensitive, especially where possession, payment terms, or the SDLT calculation change before completion.

Scroll down for the full analysis.

SDLT where a contract is substantially performed before completion and later completed by conveyance

This page explains what happens for Stamp Duty Land Tax when a land contract is treated as chargeable before formal completion, and the transaction is later completed by a conveyance such as a transfer. The point matters because there can be two SDLT events to deal with: first when the contract is substantially performed, and again when the conveyance completes the transaction.

What this rule is about

In SDLT, tax is normally linked to a land transaction completing. But some contracts are brought into charge earlier if they are substantially performed before legal completion. A common example is where the buyer takes possession or pays most of the price before the transfer is formally completed.

The source material deals with what happens next. If that earlier chargeable contract is later completed by a conveyance, the later completion is not ignored. It must also be notified, and SDLT is then worked out by comparing the tax due on completion with the tax already due on the contract.

What the official source says

The official HMRC manual says that where a contract falls within SDLT because it has been substantially performed before completion, and that contract is later completed by conveyance, the completion must also be notified.

It also says that SDLT is due on completion only to the extent that the tax due on completion is more than the tax already due on the contract.

In other words, the later conveyance can trigger a further SDLT filing obligation, but it does not automatically mean the whole tax is paid twice. The earlier SDLT position on the contract is taken into account.

What this means in practice

The practical effect is that substantial performance can create an SDLT charge before the legal transfer takes place. If the transaction then proceeds to formal completion, you do not simply rely on the earlier return and leave matters there. The later completion must also be notified.

The amount payable on completion is not a fresh full charge without credit for the earlier event. Instead, you compare:

• the SDLT due by reference to the contract when it was substantially performed, and
• the SDLT due on completion by conveyance.

If the tax due on completion is higher, the difference is payable. If it is not higher, the source material does not say that further SDLT is payable on completion, although the completion still has to be notified.

This rule is aimed at making sure the final legal completion is brought onto the SDLT record while preventing double charging on the same transaction.

How to analyse it

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

• Was there a land contract that fell within SDLT before formal completion because it was substantially performed?
• What event amounted to substantial performance? For example, was possession given, or was there some other trigger under the SDLT rules?
• Was SDLT correctly calculated and notified at that earlier stage?
• Was the contract later completed by a conveyance or other formal completion document?
• What is the SDLT position on that later completion?
• Does the tax due on completion exceed the tax already due on the contract?
• If so, what is the additional amount payable?
• Has the later completion been notified as required?

This is not just a payment question. It is also a compliance question. Even if no extra SDLT is due on completion, the manual says the completion must be notified.

Example

Illustration: A buyer exchanges contracts to buy land. Before the transfer is completed, the buyer is allowed into possession, so the contract is treated as substantially performed and comes within SDLT at that stage. An SDLT return is made and tax is paid on the basis of the contract.

Some time later, the legal transfer is executed and completed. That completion must also be notified. If the SDLT properly due on completion is greater than the amount already due on the substantially performed contract, the buyer pays the difference. If it is not greater, the completion is still notifiable, but there may be no further SDLT to pay under the rule described in the source.

Why this can be difficult in practice

The short HMRC text assumes that the reader already understands the separate rules on substantial performance, contract completion, and notification. In practice, several points can be fact-sensitive.

• It may not always be obvious whether the contract was substantially performed, especially where occupation or payment arrangements are unusual.
• The amount of tax due at the contract stage and at completion may differ if the facts relevant to the SDLT calculation have changed.
• People sometimes assume that once SDLT has been dealt with on substantial performance, nothing further is needed when the transfer completes. The source makes clear that this is wrong: the completion must also be notified.
• The manual states HMRC’s view of procedure and effect, but the detailed operation of the charge depends on the legislation and the facts of the transaction.

Key takeaways

• If a land contract is substantially performed before formal completion, it can come within SDLT before the conveyance takes place.
• If that contract is later completed by conveyance, the completion must also be notified.
• On completion, SDLT is payable only to the extent that the tax due then is more than the tax already due on the contract.

This page was last updated on 24 March 2026

Useful article? You may find it helpful to read the original guidance here: Understanding SDLT: Contract and Conveyance Notification and Tax Obligations Explained

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