LTT deferral decisions: when tax and interest become due
When an LTT deferral ends
WRA can agree to delay LTT linked to an uncertain future payment. The agreed tax must then be paid by the end of the following day after the deferral period ends.
- No interest runs on the agreed deferred amount during the deferral period.
- A refusal makes the refused amount payable by the later statutory date.
- If the real future payment exceeds the estimate, interest may run on the difference from the original payment timetable.
Scroll down for the full analysis.
Read the original guidance here:
LTT deferral decisions: when tax and interest become due
If WRA agrees to delay part of your Land Transaction Tax, known as Land Transaction Tax or LTT, you do not pay interest during that agreed delay. The tax still has to be paid when the deferral ends.
Pay late, and interest starts. If WRA refuses all or part of the request, the refused amount becomes due much sooner.
What this rule is about
Some land deals include a future payment that cannot yet be fixed. For example, a buyer may agree to pay more if planning permission is obtained. This is often called an overage clause.
LTT normally has to be paid by the return deadline, but a deferral can delay the part linked to an uncertain future payment where WRA agrees. It does not remove the tax.
That distinction matters. A delay can help cash flow, but it creates a later payment date that you must track.
What the official source says
The law lets a buyer ask WRA to defer part of the tax when part of the amount paid is uncertain or depends on an event. WRA must tell the buyer whether it agrees.
It must also state the amount deferred, the expected end date, and any conditions.
WRA’s technical guidance explains what follows from that decision. It is guidance rather than the law, but it reflects the payment and interest rules in section 61.
- If WRA agrees the request, you must pay the deferred amount by the end of the day after the deferral period ends.
- Interest on that agreed deferred amount starts only after that payment deadline.
- WRA may agree only part of the amount requested.
- If it refuses all or part, you must pay the refused amount by the later of the date you receive the decision and the normal return payment date.
- Interest on a refused amount follows the statutory interest start date after that later payment point.
- If the future amount is higher than the estimate, extra tax may be due when the amount becomes known.
What this means in practice
An agreed deferral stops interest building up on the agreed amount while you wait for the uncertain event. That is the benefit.
It is not a reason to leave the later payment unattended.
Put the expected end date and every payment condition in your diary, because the WRA notice states what WRA has actually agreed and controls the next steps. Keep that notice close.
- Read the decision notice, not just the request you sent.
- Check whether WRA agreed the whole amount or only part of it.
- Pay any amount that WRA refused to defer by the required later date.
- Monitor the event that will end the deferral, such as planning permission being granted.
- Keep evidence of when that event happened.
- Check whether the real future payment is more than the estimate used in the first return.
How to analyse it
Start with the decision, then work forwards. The key question is not simply whether WRA said yes or no.
Ask which amount WRA agreed to defer, and on what terms.
- Was the future payment genuinely uncertain or dependent on an event?
- Was a deferral request made with the first LTT return by its filing date?
- What deferred amount does WRA’s notice state?
- Did WRA refuse any part of the request?
- What expected end date and conditions does the notice give?
- Has the relevant event happened, or has the amount now become known?
- Was the original estimate lower than the amount that is now payable?
- Has a further LTT return become necessary because extra tax is due?
For later changes, section 47 matters. When an uncertain amount becomes known and extra LTT is due, you generally must make a further return within 30 days beginning with the day after that event. The section also has its own interest rule.
Example
Illustration: Beth buys land, and her contract says she will pay the seller more if she obtains planning permission. WRA agrees to defer £25,000 of LTT linked to that future payment.
Planning permission is later granted. The deferral ends.
If Beth pays the £25,000 by the end of the following day, no interest builds up on that agreed deferred amount. But suppose the land value rose more than Beth reasonably estimated, producing £30,000 of extra LTT in total. The extra £5,000 was not covered by the deferral.
On the facts used in WRA’s example, interest on that £5,000 runs back to the original transaction’s payment timetable. Paying the agreed £25,000 on time does not protect the underestimated £5,000 from interest.
Why this can be difficult in practice
The hard part is often the estimate. A future price may depend on planning, value, sales or another event that nobody can predict exactly.
An estimate can be reasonable and still turn out to be wrong.
You might think WRA’s agreement protects the whole later tax bill, but it protects only the amount WRA agreed to defer, not any extra amount caused by an underestimate. That gap can matter.
- A request may be partly agreed, leaving tax to pay straight away.
- The end date may differ from the date suggested in the request.
- Several separate future events may lead to separate deferred amounts and payment dates.
- A condition in WRA’s notice may require payment during the deferral period.
- The date you receive a refusal notice can affect when the refused amount must be paid.
- A later payment may require a further return as well as payment of extra tax.
Key takeaways
- An agreed LTT deferral delays payment; it does not cancel the tax.
- Interest on an agreed deferred amount starts after its deferred payment deadline.
- Extra tax caused by an underestimate can attract interest from much earlier.
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
- LTTA 2017 section 47 — later returns when uncertain amounts become known
- LTTA 2017 section 57 — normal deadline for paying land transaction tax
- LTTA 2017 section 58 — requests to defer tax on uncertain future payments
- LTTA 2017 section 60 — WRA notices agreeing or refusing deferral requests
- LTTA 2017 section 61 — payment and interest after WRA’s deferral decision
Official guidance
The pages below are the Welsh Revenue Authority’s guidance. Guidance is not law. It sets out how the Welsh Revenue Authority 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. the Welsh Revenue Authority can also change or withdraw guidance, and it may not cover your facts.
Where this is not settled
- The supplied statutory library did not contain the requested currency notice. Its recorded current date therefore cannot be checked.
- The supplied source does not explain the detailed review or appeal process after a refusal.
- Whether a future payment was reasonably estimated will depend on the facts and evidence available when the original return was made.
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 contract and any clause creating a future payment
- the original LTT return and deferral request
- WRA’s decision notice and any conditions attached to it
- proof of the date an event happened or an amount became known
- working papers supporting any estimate of a future payment
- proof of payment of each amount of LTT
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 Land Transaction Tax (LTT), the tax on property in Wales. It replaced Stamp Duty Land Tax in Wales on 1 April 2018, and SDLT does not apply in Wales. MY QUESTION LTT deferral decisions: when tax and interest become due [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 - LTTA 2017 section 47 - later returns when uncertain amounts become known https://www.legislation.gov.uk/anaw/2017/1/section/47 - LTTA 2017 section 57 - normal deadline for paying land transaction tax https://www.legislation.gov.uk/anaw/2017/1/section/57 - LTTA 2017 section 58 - requests to defer tax on uncertain future payments https://www.legislation.gov.uk/anaw/2017/1/section/58 - LTTA 2017 section 60 - WRA notices agreeing or refusing deferral requests https://www.legislation.gov.uk/anaw/2017/1/section/60 - LTTA 2017 section 61 - payment and interest after WRA's deferral decision https://www.legislation.gov.uk/anaw/2017/1/section/61 Guidance page from the Welsh Revenue Authority on this topic (guidance, not law): https://www.gov.wales/land-transaction-tax-returns-and-payments-technical-guidance#5589 HOW I WANT YOU TO ANSWER 1. Work from the legislation above. Read it before answering. Guidance from the Welsh Revenue Authority is its 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 statutory library did not contain the requested currency notice. Its recorded current date therefore cannot be checked. - The supplied source does not explain the detailed review or appeal process after a refusal. - Whether a future payment was reasonably estimated will depend on the facts and evidence available when the original return was made. Do not give me a conclusion you cannot support from the provisions above.
Legislation links show the Land Transaction Tax and Anti-avoidance of Devolved Taxes (Wales) Act 2017 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 3 September 2026
Useful article? You may find it helpful to read the original guidance here: LTT deferral decisions: when tax and interest become due
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