How to complete SDLT1 questions 49, 50 and 51
SDLT1 identity details
Questions 49, 50 and 51 identify the person, company or partnership buying the property. HMRC says accurate references help it process the SDLT return and warns that some errors may need a fresh return.
- Individuals normally use the lead buyer’s National Insurance number.
- Companies and partnerships use either a VAT number or the relevant UK tax reference.
- A Companies House number is not a substitute for a UK tax reference in question 51.1.
Scroll down for the full analysis.
Read the original guidance here:
How to complete SDLT1 questions 49, 50 and 51
Questions 49, 50 and 51 on an SDLT1 return ask for a number that identifies the buyer. Accurate entries can help HMRC process your stamp duty return quickly. HMRC also warns that some mistakes may be hard to correct later.
What this rule is about
An SDLT return is the form used to report a land purchase for stamp duty purposes. The required identity details vary with the buyer: a person, a company or a partnership.
This section does not work out your tax bill. It still matters. HMRC uses these details to match the return to the right person or organisation.
You might assume any official-looking company number will do. It will not. HMRC rejects the form when you use a Companies House registration number where a tax reference is required.
What the official source says
The buyer type determines the reference. HMRC’s manual gives that instruction. The manual is HMRC guidance, not the law itself. The law requires the return to be in the prescribed form and contain the prescribed information.
- Question 49 identifies the lead buyer. It requires their proper National Insurance number and date of birth.
- Do not use a temporary National Insurance number in question 49.
- If the lead buyer has no National Insurance number, leave question 49 and the date-of-birth field blank.
- Then use question 51.2 for a non-UK tax reference or, if there is none, a passport, driving licence or identity-card number.
- When you use question 51.2, question 51.3 asks for the country that issued that reference.
- For a company or partnership, answer either question 50 or question 51. Do not answer both.
- Question 50 is for a valid VAT registration number.
- If there is no VAT number, question 51.1 is for a ten-digit Company Unique Tax Reference or Partnership Unique Tax Reference supplied by HMRC.
- If there is no such tax reference, question 51.2 can use a Companies House registration number or a non-UK tax reference.
- Question 51.3 records the country that issued the reference entered in question 51.2.
What this means in practice
First decide which kind of buyer the purchase names, because that choice determines the route through these questions and prevents you from selecting the only number you happen to find. Follow that route.
For an individual, use the lead buyer’s National Insurance number where they have one; if they do not, use the alternative reference in question 51.2 and enter its issuing country in question 51.3. State the issuing country.
For an organisation, choose between VAT registration and a UK tax reference first, and consider a Companies House number only when there is no VAT number or relevant UK tax reference. Companies House comes later.
- Check whether the buyer on the contract is a person, company or partnership.
- Ask for the relevant number before the return is prepared.
- Check each digit carefully before submitting the form.
- Keep a note of where the number came from.
- Do not put a Companies House number in question 51.1.
- Do not complete both question 50 and question 51 for a non-individual buyer.
How to analyse it
Work through the questions in order, matching each route to the buyer shown on the return instead of attempting to complete every box that the form makes available. Do not fill every box.
- First, identify the buyer shown on the SDLT return.
- If it is an individual, ask whether the lead buyer has a permanent National Insurance number.
- If yes, enter that number and the lead buyer’s date of birth in question 49.
- If no, leave question 49 and the date-of-birth field blank.
- Use question 51.2 for the best available alternative reference, then complete question 51.3.
- If the buyer is a company or partnership, check for a valid VAT registration number first.
- Without a VAT number, check for the correct ten-digit UK tax reference from HMRC.
- Use question 51.2 for a Companies House number or non-UK tax reference only when neither a VAT number nor the correct ten-digit UK tax reference from HMRC is available. Check both first.
- Where you use question 51.2, record the country of issue in question 51.3.
Example
Anna is buying a home in her own name. She does not have a National Insurance number. Her conveyancer should not guess one or enter a temporary number in question 49.
Under HMRC’s instructions, question 49 and the date-of-birth box stay blank, while Anna’s passport number goes in question 51.2 and the country that issued her passport goes in question 51.3. Her passport provides the reference.
Now change the buyer. If Anna’s company is buying instead, its Companies House registration number does not belong in question 51.1. HMRC says question 51.1 needs the company’s ten-digit UK tax reference.
If the company has neither a VAT number nor that tax reference, its Companies House number can be considered for question 51.2. Question 51.1 remains unsuitable.
Why this can be difficult in practice
These questions look like routine form filling. Similar names cause confusion. The same person or business can hold several numbers. The number must match the exact question.
HMRC says accurate details matter because it may not be possible to amend them later. The legislation does allow a buyer to amend a return in some circumstances.
But it does not say that every identifier error will be accepted by HMRC’s process. That distinction matters.
- A temporary National Insurance number is not the number HMRC asks for in question 49.
- A VAT number must have nine digits, contain no letters and not start with 00, according to HMRC.
- A Company Unique Tax Reference is not the same as a Companies House registration number.
- A partnership needs its UK Partnership Unique Tax Reference where question 51.1 applies.
- Do not leave the issuing-country field out when you have used question 51.2.
- If no suitable reference is available, HMRC’s manual directs users to the Stamp Taxes helpline.
Key takeaways
- Use the identity route that matches the type of buyer.
- Never confuse a UK tax reference with a Companies House number.
- Check the numbers before filing, as HMRC may require a fresh return after some errors.
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 76 — duty to deliver an SDLT return
- FA 2003 Schedule 10 para 1 — prescribed form, information and return declaration
- FA 2003 Schedule 10 para 6 — when a buyer may amend a return
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 material does not explain which identity-field errors HMRC will accept through an amendment and which will require a fresh return.
- The prescribed SDLT return form and HMRC’s processing instructions can change, so the live form should be checked before filing.
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.
- Whether the buyer is an individual, company or partnership
- The lead individual’s National Insurance number and date of birth, if held
- A non-UK tax reference, passport, driving licence or identity-card reference where needed
- The country that issued the reference used in question 51.2
- A valid VAT number, Company Unique Tax Reference or Partnership Unique Tax Reference where applicable
- A copy of the submitted SDLT return and any HMRC response
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 complete SDLT1 questions 49, 50 and 51 [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 76 - duty to deliver an SDLT return https://www.legislation.gov.uk/ukpga/2003/14/section/76/2025-11-17 - FA 2003 Schedule 10 para 1 - prescribed form, information and return declaration https://www.legislation.gov.uk/ukpga/2003/14/schedule/10/paragraph/1/2025-11-17 - FA 2003 Schedule 10 para 6 - when a buyer may amend a return https://www.legislation.gov.uk/ukpga/2003/14/schedule/10/paragraph/6/2025-11-17 HMRC's guidance page on this topic (guidance, not law): https://www.gov.uk/hmrc-internal-manuals/stamp-duty-land-tax-manual/sdltm62520 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 material does not explain which identity-field errors HMRC will accept through an amendment and which will require a fresh return. - The prescribed SDLT return form and HMRC's processing instructions can change, so the live form should be checked before filing. 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 complete SDLT1 questions 49, 50 and 51
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