Stamp Duty: Common Mistakes and How to Reclaim Overpayments
Stamp Duty Land Tax (SDLT) is the single largest transaction cost in a property purchase, yet it is also the tax most frequently overpaid. HMRC estimates that significant sums go unclaimed each year because buyers — and sometimes their conveyancers — miss available reliefs, misclassify property types, or apply the wrong rates table.
This guide walks through the current SDLT rates, the five most common overpayment scenarios, and the precise steps to reclaim what you're owed — including the time limits that catch people out.
Jurisdiction note: SDLT applies in England and Northern Ireland. Scotland uses Land and Buildings Transaction Tax (LBTT); Wales uses Land Transaction Tax (LTT). This guide covers SDLT only.
Current SDLT Rates (2025–26)
SDLT is charged on a slice system — you pay the rate on the portion of the price falling within each band, not the whole purchase price.
Standard Residential Rates
| Purchase Price Band | SDLT Rate |
|---|---|
| Up to £250,000 | 0% |
| £250,001 to £925,000 | 5% |
| £925,001 to £1,500,000 | 10% |
| Over £1,500,000 | 12% |
First-Time Buyer Relief (on main residence only)
| Purchase Price Band | SDLT Rate (FTB) |
|---|---|
| Up to £300,000 | 0% |
| £300,001 to £500,000 | 5% |
| Over £500,000 | Standard rates apply (no relief) |
Important: FTB relief was enhanced temporarily (nil rate on first £425,000) from September 2022 to March 2025. After 1 April 2025, the thresholds reverted to the £300,000/£500,000 levels shown above.
Additional Dwelling Surcharge (ADS)
Buyers who own (or are treated as owning) one or more residential properties at the end of the day of completion must pay an additional 5% on top of standard rates for residential purchases. This applies to second homes, buy-to-let properties, and holiday homes. The surcharge applies from the first pound.
Example: Purchase of a buy-to-let property at £350,000:
- Standard SDLT: £0 on first £250k + 5% on £100k = £5,000
- ADS surcharge: 5% × £350,000 = £17,500
- Total SDLT: £22,500
The 5 Most Common SDLT Overpayment Scenarios
1. First-Time Buyer Relief Missed
This is the most straightforward error. A buyer qualifies as a first-time buyer but their solicitor applies standard rates — perhaps because the buyer mentioned they had previously owned a property abroad (which does not disqualify FTB relief in England under SDLT), or because the joint purchase rules were misunderstood.
For FTB relief to apply, all purchasers must be first-time buyers. If one buyer has previously owned a property — anywhere in the world — the relief is lost for the whole transaction.
Where the error occurs: Solicitors sometimes apply standard rates out of excessive caution. A buyer who owned property overseas but never in the UK should always claim the relief.
Reclaim value on a £400,000 purchase: Standard SDLT = £7,500. FTB SDLT = £5,000. Reclaim: £2,500.
2. Mixed-Use Property Misclassified as Residential
If a property has a non-residential element — a commercial unit, office space, agricultural land, or outbuildings used for business — it may qualify for the non-residential SDLT rates, which are substantially lower at the higher price bands.
| Non-Residential/Mixed-Use Price Band | SDLT Rate |
|---|---|
| Up to £150,000 | 0% |
| £150,001 to £250,000 | 2% |
| Over £250,000 | 5% |
Where the error occurs: Properties with annexes, offices, garages used commercially, or land attached. Solicitors may default to residential rates without analysing the use of the whole.
3. Property with an Annexe — Multiple Dwellings Relief (MDR) — Abolished June 2024
Until 1 June 2024, buyers purchasing a property that contained more than one dwelling (e.g., a house with a self-contained granny annexe) could claim Multiple Dwellings Relief (MDR). MDR calculated SDLT on the mean (average) price of each dwelling separately, then multiplied back up — this reduced SDLT significantly where a lower-priced additional dwelling dragged the rate down.
MDR was abolished for completions on or after 1 June 2024 following HMRC's consultation. No MDR claims can be made for transactions completing from that date.
However: If you purchased before 1 June 2024 and MDR was not claimed but should have been, you can still submit a reclaim within the applicable time windows (see below). HMRC has confirmed that pre-June 2024 overpayments remain claimable.
Real-world example (pre-June 2024 completion):
- Buyer purchases a £500,000 house with a self-contained annexe valued at £80,000
- Standard SDLT on £500,000: £12,500
- With MDR: mean price = (£500k + £80k) ÷ 2 = £290k. SDLT on £290k = £2,000. × 2 dwellings = £4,000. Minimum 1% of total (£5,800 × 1% = £58) — not triggered. Total SDLT under MDR: £4,000
- Overpayment if MDR missed: £8,500
4. Non-Residential Rates Applicable but Residential Charged
Beyond mixed-use, certain entirely non-residential transactions are caught: buying agricultural land with permitted development potential, purchasing a disused commercial building with consent for residential conversion. Where completion takes place before permitted development is carried out, the lower non-residential rates should apply.
This is a complex area and the line between 'residential' and 'mixed-use' has been tested extensively in the First-tier Tribunal. HMRC takes an active interest in large non-residential relief claims — take professional advice.
5. ADS Paid But Replacement Main Residence Exemption Should Have Applied
Buyers who pay the 5% Additional Dwelling Surcharge because they own another property are entitled to a full ADS refund if they sell their previous main residence within 36 months of the new purchase. Many buyers are unaware of this reclaim window and miss it.
The refund must be claimed within 12 months of the sale of the previous main residence (not 12 months of the original purchase).
Example: Buyer purchases a £600,000 new main residence in March 2024 while still owning their old property (not yet sold). ADS paid: £30,000. Old property sells in November 2025. Buyer has until November 2026 to reclaim the £30,000 ADS.
How to Reclaim: The Two Routes
Route 1: SDLT Return Amendment (12-Month Window)
The most straightforward route. An SDLT return can be amended by the buyer (or their conveyancer) within 12 months of the filing date of the original return. The filing date is typically the day of completion or within 14 days of it.
This involves submitting a corrected SDLT return showing the correct tax figure. HMRC processes the amendment and issues a repayment, usually within 8–12 weeks.
Route 2: Overpayment Relief Claim (4-Year Window)
If you are outside the 12-month amendment window, you can claim overpayment relief under Schedule 10 FA 2003. The time limit is 4 years from the date of the original SDLT return.
This claim is made by letter to HMRC's Stamp Taxes office (HMRC do not have a specific online portal for this — it is a paper/postal process). The letter must:
- Identify the transaction (title number, completion date, property address)
- State the amount of SDLT paid
- Explain the basis of the overpayment
- Quantify the amount being claimed
- Include evidence (title documents, planning records, evidence of FTB status)
HMRC's reference is Schedule 10 Finance Act 2003 paragraph 34 for overpayment relief.
SDLT Reclaim Timescales and Costs
| Route | Time Limit | Professional Cost | HMRC Processing Time |
|---|---|---|---|
| Return amendment | 12 months from filing | Conveyancer: £200–£500 | 6–8 weeks |
| Overpayment relief (Schedule 10) | 4 years from filing | Tax specialist: £500–£2,000 | 8–16 weeks |
| ADS refund (main residence replacement) | 12 months from previous sale | Conveyancer: £150–£400 | 4–8 weeks |
Section 75A Anti-Avoidance: What to Avoid
Section 75A of the Finance Act 2003 is HMRC's main anti-avoidance provision for SDLT. It is triggered where a series of transactions are structured specifically to reduce SDLT below what would be chargeable on a straightforward purchase. HMRC will look through the arrangements and charge SDLT as if the transactions were a single purchase at the higher rate.
Legitimate reliefs are not avoidance: Claiming FTB relief, mixed-use rates, or (pre-June 2024) MDR on genuinely qualifying properties is entirely lawful. Section 75A targets artificial schemes — typically marketed "SDLT mitigation" arrangements involving sub-sale relief, partnership structures, or annuity arrangements — that HMRC has largely closed down.
Do not confuse legitimate relief claims with marketed avoidance schemes. HMRC successfully challenges the latter and pursues penalties alongside underpaid tax.
Getting Help
For straightforward cases (FTB relief missed, ADS refund), your original conveyancer can typically handle the amendment for £200–£500. For more complex cases (MDR pre-June 2024, mixed-use classification, non-residential rates), a specialist SDLT adviser or property tax solicitor is worth the investment — reclaims can run into tens of thousands of pounds.
Always check the filing date on your original SDLT5 completion certificate (the certificate HMRC issues after your return is processed) to confirm which window is still open. Acting promptly is essential: the 4-year window closes absolutely, and there is no HMRC discretion to extend it.
Further Reading
- How to Reclaim Overpaid Stamp Duty (SDLT) from HMRC — the complementary step-by-step guide to submitting your claim, what HMRC requires, and what to do if they open an enquiry
- Stamp Duty Land Tax (SDLT): Rates, First-Time Buyer Relief, and How to Calculate Your Bill — full rates table, worked examples at four price points, and the ADS explained in detail
- Stamp Duty Calculator UK: How Much Will You Pay in 2025? — a quick-reference guide to calculating your SDLT bill before you exchange