Stamp duty when building work is part of the land deal
Building work can affect stamp duty
A promise to build for the seller may increase the amount used to work out SDLT. The result often depends on where and when the work takes place.
- Work on the seller’s separate land can be added to the SDLT amount.
- Post-completion work on land you buy may be left out.
- Keep the contract, plans and cost evidence.
Scroll down for the full analysis.
Read the original guidance here:
Stamp duty when building work is part of the land deal
If you buy land and also promise to build something, stamp duty may be based on more than the cash price. The key question is where the work will happen. HMRC’s examples show SDLT can shift by £750,000 or more.
What this rule is about
Stamp duty land tax looks at everything you give to get land, not just the money paid on completion. That can include construction, repair or improvement work promised to the seller.
There is an important exception. Work may be left out when it is done after the SDLT effective date on land you are buying, or on land you already hold.
What the official source says
HMRC’s manual gives two contrasting examples. It reflects the statutory rule on construction work. The manual is HMRC guidance, not law.
- The work must be done after the SDLT effective date.
- It must be done on land bought in the deal, or land already held by you or someone connected with you.
- For this purpose, neither the seller nor anybody connected with the seller can be under a requirement to carry out any of the work.
- Failure adds the work’s value to SDLT.
- Its value is the open-market cost of having the work done.
What this means in practice
Seller-side work can count as price. A building promise for the seller’s separate site may raise SDLT.
Required post-completion work on bought land may qualify. The wording of the contract matters.
- List every cash payment, promised work and other benefit in the deal.
- Check who owns the land where the work will take place.
- Check when the work is required to happen.
- Keep evidence supporting the stated value of the work.
How to analyse it
Start with the whole bargain. Cash alone does not settle SDLT. Other agreed value can also count.
- Read the sale contract, specifications and any linked agreement together.
- Identify the work you have promised to carry out.
- Find the SDLT effective date, which is normally completion.
- Map the site of the work. Are you buying that land or do you already hold it?
- Check whether the seller must carry out any of the work.
- Value any work that does not meet every condition.
Example
HMRC’s first example involves a construction company buying a plot for £1 million. It also promises to build a workshop worth £750,000 on the seller’s nearby land. That site is not land being bought by the company.
HMRC therefore treats the amount used for SDLT as £1.75 million.
In the second example, the company pays a council £5 million and must build a £1 million leisure centre after completion on part of the land it bought. HMRC says the SDLT amount is £5 million, not £6 million.
Why this can be difficult in practice
The distinction sounds narrow. It is not. The plan, the title boundary, or a condition in the contract may ultimately determine whether a large building cost is included.
- A nearby plot owned by the seller is not the same as part of the plot you buy.
- “After completion” may not answer the question if another SDLT effective date applies.
- A project cost is not automatically its open-market value.
- Side letters and development agreements may contain promises missing from the transfer document.
Key takeaways
- Building work can be part of the price for SDLT.
- Work on the land you buy after the effective date may be excluded.
- The contract, site ownership, timing and value all matter.
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 50 — schedule 4 rules for the amount paid
- FA 2003 Schedule 4 para 1 — money or value given for the land
- FA 2003 Schedule 4 para 10 — when building works count in the price
- FA 2003 section 119 — the date used for SDLT purposes
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
- It can be unclear whether a particular obligation is building work, a service, or part of the land price.
- The timing of the work and the land on which it is done may need to be proved from the contract and project records.
- A reliable market value for the promised work may be disputed.
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 any side agreements
- Plans showing where the work will be done
- The completion date and the actual work timetable
- Costings, tenders and evidence of the work’s market value
- Details of any connection between the parties
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 Stamp duty when building work is part of the land deal [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 50 - schedule 4 rules for the amount paid https://www.legislation.gov.uk/ukpga/2003/14/section/50/2025-11-17 - FA 2003 Schedule 4 para 1 - money or value given for the land https://www.legislation.gov.uk/ukpga/2003/14/schedule/4/paragraph/1/2025-11-17 - FA 2003 Schedule 4 para 10 - when building works count in the price https://www.legislation.gov.uk/ukpga/2003/14/schedule/4/paragraph/10/2025-11-17 - FA 2003 section 119 - the date used for SDLT purposes https://www.legislation.gov.uk/ukpga/2003/14/section/119/2025-11-17 Guidance page from HMRC on this topic (guidance, not law): https://www.gov.uk/hmrc-internal-manuals/stamp-duty-land-tax-manual/sdltm04060a HOW I WANT YOU TO ANSWER 1. Work from the legislation above. Read it before answering. Guidance from HMRC 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 - It can be unclear whether a particular obligation is building work, a service, or part of the land price. - The timing of the work and the land on which it is done may need to be proved from the contract and project records. - A reliable market value for the promised work may be disputed. 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 31 August 2026
Useful article? You may find it helpful to read the original guidance here: Stamp duty when building work is part of the land deal
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