LTT transition rules: contracts exchanged before 1 April 2018
Pre-April 2018 Welsh contracts
A Welsh property sale that crossed the 1 April 2018 change to LTT cannot be classified from its completion date alone.
- Check the exchange date.
- Check any early possession or major payment.
- Check the date and nature of any contract change.
Scroll down for the full analysis.
Read the original guidance here:
LTT transition rules: contracts exchanged before 1 April 2018
LTT transition rules for contracts made before 1 April 2018
Land Transaction Tax replaced stamp duty land tax in Wales on 1 April 2018. If your Welsh property contract began before then but finished later, the answer may not follow the completion date alone. Depending on the order of events, SDLT, LTT, or both taxes may apply at different points.
What this rule is about
Most property purchases follow a simple path: contracts are exchanged, then the sale completes. Unlike that usual sequence, the 2018 changeover was different. A contract could have started while SDLT still applied, then reached a key stage after LTT began.
For that reason, the official table tracks three dates: on or before 17 December 2014, from 17 December 2014 to 31 March 2018, and from 1 April 2018 onwards. It also tracks changes to the contract and an early trigger called substantial performance.
That distinction can matter a great deal.
What the official source says
Welsh Government guidance gives a timetable-based result. It does not say that every sale finishing after 1 April 2018 falls under LTT. Instead, it asks what happened first and when.
- If contracts were exchanged on or before 17 December 2014 and the sale later completed, the table shows SDLT on completion.
- If the contract had already reached substantial performance by that earlier date, the table shows SDLT at that stage and again on completion.
- If contracts were exchanged by that earlier date, then changed between 17 December 2014 and 31 March 2018, the table shows LTT on completion.
- If substantial performance happened in that middle period, the result can be SDLT at that stage and SDLT or LTT on completion, depending on whether and when the contract changed.
- If contracts were exchanged between 17 December 2014 and 31 March 2018, then completed from 1 April 2018, the table shows LTT on completion.
- For those middle-period contracts, if the early trigger happened before completion, the table can show SDLT at that stage and LTT on completion.
Substantial performance has a specific legal meaning. Broadly, it can happen when the buyer takes possession of almost all the property, or pays almost all the price. Exact facts matter.
What this means in practice
Do not use the completion date as a shortcut. A sale completed after LTT began may still have an SDLT consequence because of an earlier contract or early trigger.
Equally, a contract change can alter the result shown in the transition table. Depending on whether a variation happened before, after, or at the same time as the early trigger, the source records different outcomes.
- Keep the exchange date, not just the completion date.
- Check whether anyone moved in, took rents, or paid most of the price early.
- Find every agreed change to the original contract.
- Put the events in date order before deciding which tax applies.
- Do not assume that a reference to both taxes means the same payment is charged twice.
How to analyse it
Start with the documents and build a short timeline. This is the part people often get wrong: a small change in the order of events can change the table result.
- Was the land in Wales?
- When did the parties exchange contracts?
- Did the sale complete before or after 1 April 2018?
- Did substantial performance happen, and on what date?
- Was the contract varied?
- If it was varied, did that happen before or after the early trigger?
- Which row in the official table matches that full sequence?
For example, the table distinguishes between a contract changed before substantial performance and one changed after it. Those facts may look similar in a file. Published guidance does not treat them the same way.
Example
Illustration: Aled exchanged contracts on 10 March 2018 and completed on 10 April 2018. Aled’s contract was not substantially performed before completion. This matches the source row for exchange between 17 December 2014 and 31 March 2018, followed by completion from 1 April 2018. On completion, the table shows LTT.
Now change one fact. If Aled had substantially performed the contract before completion, the source table shows SDLT at that earlier stage and LTT on completion. As the table does not provide rates or a calculation, this example does not state an amount due.
Why this can be difficult in practice
Old transactions are hard because the key evidence may sit in several places. A completion statement may not show when possession started. An email or side letter, rather than a formal deed, may record a contract change.
What counts as a variation is also important. Although the supplied official page uses that word, it does not define it. It is therefore unsafe to assume that every practical change, delay, or discussion changes the tax result.
- People often look only at completion. The table requires a wider timeline.
- Early access or rent receipts may matter, even where legal ownership transferred later.
- A change to the deal needs its own date and document.
- The table is historic guidance, not a current LTT rates guide.
- The supplied material does not explain every possible combination of events.
Key takeaways
- For Welsh contracts spanning 1 April 2018, timing decides the tax result.
- Exchange, contract changes, early performance and completion must be put in order.
- The official table can show SDLT, LTT, or consequences under both taxes at separate stages.
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 10 — timing rules for contracts and completed transfers
- LTTA 2017 section 14 — when a contract has been substantially performed
- LTTA 2017 section 78 — power to make transitional tax regulations
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 material does not include the transitional regulations that underpin the table, so this page cannot resolve questions about whether a particular contract change was a variation.
- The source table does not cover every possible fact pattern or explain how tax amounts are calculated where both SDLT and LTT appear.
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 contract and its exchange date
- The transfer and completion date
- Any deed, side letter, or agreed contract change and its date
- Evidence of possession, rent, or payments that may show substantial performance
- Earlier SDLT returns and payment records, where relevant
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 transition rules: contracts exchanged before 1 April 2018 [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 10 - timing rules for contracts and completed transfers https://www.legislation.gov.uk/anaw/2017/1/section/10 - LTTA 2017 section 14 - when a contract has been substantially performed https://www.legislation.gov.uk/anaw/2017/1/section/14 - LTTA 2017 section 78 - power to make transitional tax regulations https://www.legislation.gov.uk/anaw/2017/1/section/78 Guidance page from the Welsh Revenue Authority on this topic (guidance, not law): https://www.gov.wales/transitional-guidance-introduction-of-land-transaction-tax#5099 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 material does not include the transitional regulations that underpin the table, so this page cannot resolve questions about whether a particular contract change was a variation. - The source table does not cover every possible fact pattern or explain how tax amounts are calculated where both SDLT and LTT appear. 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 4 September 2026
Useful article? You may find it helpful to read the original guidance here: LTT transition rules: contracts exchanged before 1 April 2018
Search Land Tax Advice with Google
