Multiple Dwellings Relief (MDR) is one of the most valuable — and most contested — SDLT reliefs of the last decade. Until it was abolished by the Spring Budget 2024 for transactions completing on or after 1 June 2024, MDR allowed buyers of property that included two or more "dwellings" to calculate SDLT on the average price per dwelling rather than the total. For homes with self-contained annexes — granny flats, separate guest cottages, converted outbuildings — the saving could be substantial.
Even though MDR no longer applies to new purchases, the four-year overpayment relief window means thousands of buyers who completed before June 2024 may still be entitled to claim. Many didn't at the time because their solicitor didn't flag it.
How MDR worked
Under MDR, the SDLT calculation worked as follows: take the total purchase price, divide it by the number of dwellings, calculate SDLT on the average dwelling price, then multiply by the number of dwellings. A minimum SDLT rate of 1% of the total price applied as a floor.
Example: a £900,000 house with a self-contained annexe (two dwellings). Without MDR, SDLT at standard rates was £35,000 (under pre-April-2025 rates). Under MDR: average dwelling price £450,000; SDLT on £450,000 at standard rates was £10,000; multiplied by two = £20,000. Saving: £15,000.
The MDR cut-off
MDR was abolished for SDLT transactions with an effective date on or after 1 June 2024. Transactions completing before that date can still claim MDR, including via overpayment relief if it wasn't claimed at the time. The general 4-year deadline applies (calculated from completion).
The "self-contained dwelling" test
The crucial — and frequently contested — question was whether an annexe qualified as a separate dwelling. HMRC and the tax tribunals applied a substance-over-form test: the annexe had to be capable of independent use as a residence. The factors that mattered most were:
Separate facilities. The annexe had to have its own kitchen and its own bathroom. A bedroom with a kettle and a microwave was not enough. The kitchen had to be functional — capable of preparing meals, with proper plumbing and electrical connections.
Separate entrance. The annexe had to be capable of being entered from outside without going through the main dwelling. Internal-only access was a strong negative factor.
Privacy and independence. The annexe had to be capable of being "lockable" from the main house — i.e. its occupants could come and go without disturbing the main dwelling. A lockable internal door was usually required.
Independent utilities. Separately metered utilities helped (though weren't mandatory); separate council tax bands (where they existed) were strong evidence.
Recent case law
The First-tier Tribunal heard many MDR cases between 2018 and 2024. The trend was toward stricter interpretation. Cases like Fiander, Doe, and Mullane rejected MDR claims where the annexe failed one or more of the substantive tests. The most common reasons for rejection were: kitchen too rudimentary; no lockable internal door; entrance only through the main dwelling. Successful claims tended to involve genuine, established annexes with all four indicators of independence.
Can you still claim?
If you bought a property with what you believe to be a self-contained annexe before 1 June 2024, and you did not claim MDR on your original SDLT return, you may be entitled to a refund via overpayment relief — provided you are still within the four-year window from completion. The claim is filed via an amendment to the SDLT return.
Documentation is critical: floor plans showing layout and separate access; photographs of the annexe's kitchen, bathroom, and entrance; the property listing; the EPC; and any separate council tax records. Our MDR deep dive covers the claim process in detail.
Don't confuse MDR with the "subsidiary dwelling" exemption
These are different reliefs. MDR (now abolished for new purchases) reduces overall SDLT. The subsidiary dwelling exemption avoids the additional-dwelling surcharge in some cases where an annexe and main house are bought together as a single residence. Both have their own tests — speak to a specialist if you think either applies.
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