Landmark Stamp Duty Cases
Essential SDLT case law shaping property tax interpretation in 2026. From Tower One St George Wharf to MDR abolition cases, understand the court decisions that impact your stamp duty liability.
In this article
Stamp Duty Land Tax case law continues to evolve through tribunal and court decisions that clarify ambiguous provisions, test anti-avoidance rules, and establish precedents for property transactions. Understanding landmark cases is essential for conveyancers, tax advisers, and property buyers navigating complex SDLT scenarios in 2026.
Tower One St George Wharf v HMRC [2025] EWCA Civ 1588
Case Background
Tower One St George Wharf involved an intra-group property transfer where the taxpayer structured the transaction to minimize SDLT using group relief provisions. HMRC challenged the arrangement under s75A, the targeted anti-avoidance rule (TAAR) designed to counter artificial arrangements that exploit SDLT reliefs.
Court of Appeal Decision
In January 2026, the Court of Appeal ruled in favor of HMRC, establishing that s75A should be interpreted broadly to capture arrangements whose main purpose, or one of their main purposes, is to obtain an SDLT advantage. The court rejected the taxpayer's argument that commercial rationale alone shields transactions from s75A scrutiny.
This decision significantly expands HMRC's powers to challenge intra-group transactions and represents a major shift in how s75A is applied. The ruling emphasizes that even transactions with genuine commercial elements can be caught by s75A if obtaining an SDLT advantage is a main purpose.
Impact on Taxpayers
- Intra-group property transactions now face heightened scrutiny
- Commercial rationale alone insufficient to avoid s75A challenge
- Tax advisers must carefully document business purposes beyond SDLT savings
- Group relief arrangements require comprehensive justification
- Increased risk of HMRC enquiries into corporate restructuring
Tretyakov v HMRC
Mixed-Use Classification Issue
Tretyakov concerned a property with both residential accommodation and commercial office space. The taxpayer argued the property should be classified as mixed-use, attracting lower non-residential SDLT rates and avoiding the 3% (now 5%) additional property surcharge.
Tribunal Ruling
The First-tier Tribunal confirmed that partial commercial use does not automatically qualify a property for mixed-use classification. The tribunal emphasized that the commercial element must be substantial and integral to the property's character, not merely ancillary to residential use.
This decision tightened mixed-use classification criteria, making it harder for taxpayers to argue that small-scale commercial activities (such as home offices or occasional business use) convert residential property to mixed-use for SDLT purposes.
Practical Implications
- Home offices and small commercial spaces unlikely to qualify as mixed-use
- Commercial element must be substantial and integral, not ancillary
- 5% additional property surcharge applies unless genuinely mixed-use
- Planning permission and actual use both relevant to classification
- Properties marketed as residential face higher burden of proof
Hyman v HMRC and MDR Cases
Hyman v HMRC: Annex Classification
Hyman involved a property with a main house and an annex. The taxpayer claimed Multiple Dwellings Relief (MDR), arguing the annex constituted a separate dwelling. The tribunal examined whether annexes with shared facilities and limited independence qualify as separate dwellings for MDR purposes.
The case established important principles for determining when annexes, granny flats, and subsidiary accommodation qualify as separate dwellings, focusing on factors such as independent access, self-contained facilities, and degree of separation from the main property.
MDR Abolition and Transitional Cases
Multiple Dwellings Relief was abolished on 1 June 2024, with transitional protection for contracts exchanged before 6 March 2024 (Budget 2024 announcement date) and completed by 31 May 2024. Numerous tribunal cases addressed transitional rules, examining:
- Whether contracts exchanged pre-6 March 2024 qualify for protection
- Completion date requirements and extensions
- Treatment of contract variations post-6 March 2024
- Anti-forestalling provisions and backdating attempts
Current Position (2026)
MDR remains abolished. Properties with multiple dwellings purchased after 1 June 2024 (unless protected by transitional rules) attract SDLT calculated on the total purchase price without averaging relief. This significantly increased tax liability for portfolio landlords and multi-unit property investors.
SDLT Landscape: Before vs. After April 2025
| Provision | Before April 2025 | After April 2025 |
|---|---|---|
| Nil-rate Band | £250,000 | £125,000 |
| Additional Property Surcharge | 3% | 5% |
| Corporate Rate (17%+ Residential) | 15% | 17% |
| Multiple Dwellings Relief | Abolished June 2024 | Still Abolished |
| s75A Anti-Avoidance | Narrower interpretation | Broadened (Tower One, Jan 2026) |
| Mixed-Use Classification | More flexible | Tightened (Tretyakov) |
Key Change: April 2025 reforms increased SDLT burden significantly, while concurrent case law developments (Tower One, Tretyakov) closed planning opportunities, creating a more restrictive environment for property transactions.
Impact on Property Transactions in 2026
For Property Buyers
- Mixed-use claims require stronger evidence following Tretyakov
- Annex properties less likely to qualify for reduced rates post-MDR abolition
- 5% surcharge on additional properties increases buy-to-let costs substantially
- First-time buyer relief unchanged but nil-rate band halved to £125k
For Corporate Buyers
- Tower One decision increases risk of s75A challenges on intra-group transfers
- 17% rate applies to residential properties over £500k (corporate rate)
- Comprehensive documentation required for corporate restructuring
- Tax planning opportunities significantly reduced post-April 2025
For Tax Advisers
- Client advice must reflect broader s75A interpretation and heightened HMRC scrutiny
- Mixed-use classification requires detailed analysis of commercial element
- MDR transitional rules no longer relevant for post-June 2024 transactions
- Increased importance of clearance applications for complex structures
Key Takeaways from Landmark Cases
Tower One St George Wharf (2026) established that s75A applies broadly to intra-group transactions where obtaining an SDLT advantage is a main purpose, regardless of commercial justification.
Tretyakov confirmed that partial commercial use is insufficient for mixed-use classification; the commercial element must be substantial and integral, not ancillary.
Hyman and MDR cases remain relevant for understanding annex classification principles, though MDR itself is abolished (June 2024) and unavailable for current transactions.
Combined with April 2025 reforms (5% surcharge, £125k nil-rate band, 17% corporate rate), recent case law creates a significantly more restrictive SDLT environment.
Professional advice is essential for complex transactions, group restructuring, mixed-use claims, and any arrangement potentially caught by s75A anti-avoidance provisions.
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Emma Richardson, MRICS
Chartered Surveyor & Property Tax Specialist
Emma Richardson is a RICS-qualified Chartered Surveyor with over 12 years of experience in UK property taxation. She founded Stamp Duty Calculator to help buyers understand the complex world of property transaction taxes.