Deferring SDLT when a later property payment is uncertain
Deferred SDLT at a glance
Where a later land payment depends on an uncertain future event, a buyer may be able to defer SDLT on that part. The fixed upfront payment is not deferred.
- Planning permission can be the event that fixes a later payment.
- HMRC’s examples require a further return after that event.
- The examples use January 2021 rates and are not current rate guidance.
Scroll down for the full analysis.
Read the original guidance here:
Deferring SDLT when a later property payment is uncertain
Where part of the price for land depends on a future event, you may be able to defer some stamp duty land tax. This can matter when planning permission controls a later payment. It does not remove the tax. It can delay tax on the uncertain part.
What this rule is about
Some land deals split the price into two parts. You pay one amount when the deal completes. You may pay more later if something happens.
Planning permission is a common example. For each number of homes approved, a contract can require the seller to receive extra money. At completion, nobody knows how many homes will receive permission.
Where a future payment is uncertain, the law normally sets rules for calculating tax, but Section 90 offers the buyer a separate route to defer tax on the uncertain element in some cases. Section 90 limits this route.
What the official source says
HMRC’s manual gives examples of a successful application. In those examples, the later amount depended on planning permission, while at least one possible date for a later payment fell more than six months after completion. That timing matters.
- A future payment must be contingent or uncertain when the deal takes effect.
- More than six months after completion, at least one future payment date must fall, or could fall.
- To defer the payment, the buyer must apply.
- Tax still falls due in the normal way on money already paid.
- When making the application, the buyer must still pay tax on any amount that is fixed and can be calculated then.
- In the examples, getting planning permission is the event that fixes the later amount.
This distinction is the key point. Deferral covers the unknown element, not the whole deal.
What this means in practice
Suppose you pay a fixed amount on completion and agree an extra payment if planning permission is granted, with the later sum remaining unknown until that event occurs. An accepted application may mean you pay SDLT first on the fixed amount only.
Once permission is granted, the buyer can work out the total price. HMRC’s examples say the buyer then sends a further return within 30 days of that event and pays the extra SDLT.
- Keep the fixed payment separate from the possible later payment.
- Read the contract closely to identify the event that triggers more money.
- Record when that event happens.
- Work out the total amount paid under the deal once it happens.
- Calculate the SDLT due on that total, using the rules that applied to the transaction.
- Subtract SDLT already paid to find the further amount due.
A successful deferral might appear to mean that no tax is due until the planning issue is settled. It does not. Straight away, the upfront amount still matters.
How to analyse it
Start with the contract, not the label used for the payment. Calling a sum an overage payment does not by itself show that it is uncertain.
- What amount was paid when the land deal completed?
- What later payment does the contract require?
- Does that payment depend on an uncertain future event?
- Could at least one payment date be more than six months after completion?
- Was an application to defer payment made and accepted?
- At the application date, which part of the price was fixed?
- What event later fixed the extra amount?
- When did that event occur?
Then keep two calculations. One shows SDLT due on the amount paid upfront. Another updates the position once the later amount is known.
Example
HMRC’s first example concerns land bought in January 2021. The buyer pays £350,000 at once. For each set of 50 homes that receives planning permission, the contract also provides £50,000. The buyer expects approval for 200 homes.
HMRC says the buyer successfully applies to defer SDLT on the uncertain later payment. Using the rates in its 2021 example, SDLT on £350,000 is £7,000: £0 on the first £150,000, £2,000 on the next £100,000, and £5,000 on the remaining £100,000.
After permission arrives for 200 homes, the buyer pays a further £200,000. The total price is now £550,000. HMRC’s calculation gives total SDLT of £17,000. As £7,000 was already paid, a further £10,000 is due.
Within 30 days of the planning permission event, HMRC says the buyer needs to send a further return. These figures are an historical illustration, not a rate calculation for a current purchase.
Why this can be difficult in practice
Often, the arithmetic is not the hard part. Instead, you must decide what the contract really requires, when the relevant event happened, and whether the later sum was truly uncertain at the right time. That can be difficult.
- A payment may be delayed without being uncertain.
- A contract can have several trigger events, rather than one clear event.
- Permission for more or fewer homes than expected may change the later amount.
- Planning permission may be granted in stages.
- The land and the rate rules may not match the simple facts in HMRC’s examples.
- The manual does not set out every detail of the application process.
HMRC’s second example makes another useful point. Initially, the buyer pays £100,000, so the manual shows no SDLT at that stage. Permission later covers 300 homes, producing a £300,000 payment and a total price of £400,000. The manual’s 2021 calculation gives SDLT of £9,500 then.
Key takeaways
- Deferral may be available for a genuinely uncertain later payment.
- You still pay SDLT on the fixed amount paid upfront.
- When the trigger event happens, the tax position must be updated.
Technical analysis
For advisers, and for anyone who wants to check the law behind this page. You do not need this section to understand the guidance above.
Legislation
- FA 2003 section 51 — how uncertain future payments are valued
- FA 2003 section 90 — deferring tax on later uncertain payments
Official guidance
The pages below are HMRC’s guidance. Guidance is not law. It sets out how HMRC reads the legislation, and it is not binding on you, on a tribunal or on a court. Where guidance and the legislation differ, the legislation wins. HMRC can also change or withdraw guidance, and it may not cover your facts.
Where this is not settled
- The source does not explain the application form, the evidence HMRC expects, or every ground on which HMRC may refuse an application.
- The source does not establish the SDLT rates for a transaction taking place today. Rates and reliefs depend on the transaction date and facts.
- Whether a payment is genuinely uncertain can depend on the wording of the sale contract and the event that triggers it.
Evidence you would need
This kind of case is decided on the facts of the individual property. These are the records that usually settle it, and the ones an adviser would ask you for.
- The signed sale contract and any overage or deferred-payment clause
- The completion date and amounts paid at that date
- The future event that controls the later payment
- Evidence of when that event happened
- The calculation of the extra payment and SDLT
Explore this with an AI
Readers often want to test their own situation. Copy the prompt below into ChatGPT, Claude or Gemini. It hands the model the actual legislation for this page rather than letting it answer from memory, and tells it to be explicit about what is uncertain. What comes back is information, not advice – check it against the links above.
I am researching UK Stamp Duty Land Tax (SDLT), which applies in England and Northern Ireland. MY QUESTION Deferring SDLT when a later property payment is uncertain [Replace this with your own situation: what you are buying, the price, the dates, who the buyer is, and what you plan to do with the property.] THE LAW THIS TURNS ON - FA 2003 section 51 - how uncertain future payments are valued https://www.legislation.gov.uk/ukpga/2003/14/section/51/2025-11-17 - FA 2003 section 90 - deferring tax on later uncertain payments https://www.legislation.gov.uk/ukpga/2003/14/section/90/2025-11-17 HMRC's guidance page on this topic (guidance, not law): https://www.gov.uk/hmrc-internal-manuals/stamp-duty-land-tax-manual/sdltm50900a HOW I WANT YOU TO ANSWER 1. Work from the legislation above. Read it before answering. HMRC guidance is HMRC's view of the law, not the law, and does not bind a tribunal or a court. 2. Tell me what the rule actually requires, in plain English. 3. Tell me which facts decide the answer, and which facts would change it. 4. Tell me what evidence I would need to support the position. 5. Be explicit about anything unsettled or fact-sensitive. Do not guess. 6. Your training data has a cutoff and SDLT rates and reliefs change at fiscal events. Say so if you are not sure the law is current. POINTS ALREADY KNOWN TO BE UNCERTAIN ON THIS TOPIC - The source does not explain the application form, the evidence HMRC expects, or every ground on which HMRC may refuse an application. - The source does not establish the SDLT rates for a transaction taking place today. Rates and reliefs depend on the transaction date and facts. - Whether a payment is genuinely uncertain can depend on the wording of the sale contract and the event that triggers it. Do not give me a conclusion you cannot support from the provisions above.
Legislation links show Finance Act 2003 as it stood on 2025-11-17. The law may have changed since, and the rules that apply are those in force on the date of your transaction. The official guidance this page is based on is here.
This page was last updated on 1 September 2026
Useful article? You may find it helpful to read the original guidance here: Deferring SDLT when a later property payment is uncertain
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