How to apply to defer stamp duty on an uncertain future payment
Deferring SDLT on a future payment
You may be able to delay SDLT on part of a property price that remains contingent or uncertain. HMRC says you must apply in writing within 30 days after the effective date.
- Explain the future payment and its likely timing
- Calculate SDLT on the full amount and the deferred part
- Pay SDLT that relates to fixed or already known amounts
Scroll down for the full analysis.
Read the original guidance here:
How to apply to defer stamp duty on an uncertain future payment
How to apply to defer stamp duty on an uncertain future payment
If part of your property price depends on something that may happen later, you may be able to delay paying some stamp duty. HMRC allows 30 days for written applications. Count from the transaction’s effective date.
What this rule is about
Some property deals include a later payment. Planning permission may trigger a higher payment. So may a development reaching an agreed sales target. That later amount may be uncertain when you buy.
Normally, stamp duty land tax, or SDLT, still takes account of that amount. The law tells you to assume a contingent payment will become payable. For an uncertain amount, you use a reasonable estimate.
That can mean tax becomes due before you know the final bill. Deferral offers a way to postpone the part that relates to the future amount.
What the official source says
HMRC’s manual points to regulations 10 to 28 of the Stamp Duty Land Tax (Administration) Regulations 2003. A written application is required, and HMRC does not accept one that arrives late.
- Your application must reach HMRC within 30 days after the effective date.
- Completion normally provides the effective date, although the law sets a different date for certain transactions.
- You must identify the buyer.
- You must give the location of the land or property.
- You must explain why the future payment is contingent or uncertain.
- You must state how much of the price you want HMRC to defer.
- You must give as much detail as possible about when payments may happen.
- You must give a reasoned view on when the uncertainty will end.
- You must calculate SDLT on the full amount, including the future payment.
- You must also calculate the SDLT amount that you want to defer.
The legal gateway has its own limits. The future payment must still be contingent or uncertain on the effective date. At least one possible payment date must fall more than six months after that date, or be capable of doing so.
What this means in practice
You cannot use deferment to delay all your SDLT. It only concerns the tax that depends on the uncertain future payment. Tax on money already paid remains payable. Tax on amounts you can already work out also remains payable.
Once you make an application, HMRC’s manual says it suspends the amount covered by it while HMRC reaches a decision on the application, which you must make in writing within 30 days after the effective date. The manual says to send it to the Stamp Office, marked “SDLT Deferment Applications”.
- Check the effective date before you count the 30 days.
- Prepare the SDLT calculations before you send the application.
- Keep the contract clause that creates the future payment.
- Explain the payment timetable, even if it remains uncertain.
- Pay any SDLT that does not relate to the requested deferral.
This is the part people can miss: a payment can be uncertain, yet still fall outside the deferral rule if every possible payment date falls within six months.
How to analyse it
Start with the payment clause, not with its label. Calling something an earn-out or an overage payment does not settle the issue. Identify the payment trigger, possible amount, and possible due date.
- Find the transaction’s effective date.
- Identify each future payment in the contract.
- Ask whether an uncertain future event controls payment or its amount.
- Ask when each payment may fall due.
- Establish whether at least one date falls, or could fall, more than six months later.
- Work out the full SDLT figure using the required assumption or estimate.
- Separate the SDLT linked to the future amount from SDLT due now.
- Send the written application within the stated 30-day period.
What actually decides the result? The wording of the payment clause and the timing of the possible payment. A vague description will not replace those facts.
Example
Illustration: Maya buys land for £500,000. Her contract says she may pay a further £100,000 if planning permission is granted. The payment could become due nine months after completion. Maya calculates SDLT using the full amount required by the rules, then separately calculates the part linked to the possible £100,000 payment.
She can apply in writing to defer that second part, provided she applies within 30 days after the effective date and gives HMRC the required details. She cannot use the application to postpone SDLT on the fixed £500,000 price.
Why this can be difficult in practice
Future-payment clauses can include several events, multiple dates and possible amounts. A payment can seem uncertain initially. The contract may nevertheless already provide enough information to work it out. Equally, an amount can remain uncertain even where the contract gives a maximum figure.
- People often count 30 days from exchange rather than checking the effective date.
- People may provide a total SDLT figure but omit the deferred amount calculation.
- A future payment due within six months may not meet the timing condition.
- The application needs more than a copy of the contract without an explanation.
- HMRC may ask for more information before deciding the application.
- Before reaching its decision, HMRC must tell you what information it requires and allow you at least 30 days to provide it.
- If you do not provide that information in time, HMRC may refuse the application.
HMRC’s manual is guidance, not the law itself. The legislation and regulations control the result, and the supplied statutory material only records changes known to be in force up to 17 November 2025.
Key takeaways
- Apply within 30 days after the effective date.
- Deferral only covers SDLT linked to a qualifying uncertain future payment.
- Give HMRC clear facts, timing details and both SDLT calculations.
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 — valuing contingent and uncertain future payments
- FA 2003 section 90 — deferring tax on uncertain future payments
- FA 2003 section 119 — setting the transaction’s effective date
- Stamp Duty Land Tax (Administration) Regulations 2003 regs. 10–28 — making and deciding deferment applications (could not parse a provision)
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 supplied HMRC page does not explain what follows after HMRC refuses an application.
- The supplied source does not set out how HMRC decides whether to accept an application beyond the information process.
- The current status of the legislation and regulations after 17 November 2025 needs verification.
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 sale contract and any document describing the future payment
- The property’s address or clear location details
- A timetable showing when payments may become due
- An explanation of what makes the payment uncertain
- Calculations of SDLT on the full expected amount and the amount to defer
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 How to apply to defer stamp duty on an uncertain future payment [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 - valuing contingent and uncertain future payments https://www.legislation.gov.uk/ukpga/2003/14/section/51/2025-11-17 - FA 2003 section 90 - deferring tax on uncertain future payments https://www.legislation.gov.uk/ukpga/2003/14/section/90/2025-11-17 - FA 2003 section 119 - setting the transaction's effective date https://www.legislation.gov.uk/ukpga/2003/14/section/119/2025-11-17 HMRC's guidance page on this topic (guidance, not law): https://www.gov.uk/hmrc-internal-manuals/stamp-duty-land-tax-manual/sdltm50910 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 supplied HMRC page does not explain what follows after HMRC refuses an application. - The supplied source does not set out how HMRC decides whether to accept an application beyond the information process. - The current status of the legislation and regulations after 17 November 2025 needs verification. 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: How to apply to defer stamp duty on an uncertain future payment
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