The 6+ dwellings SDLT rule.

One of the quietest savings in UK property tax: buy six or more dwellings in a single transaction and the purchase can be taxed at non-residential SDLT rates instead of residential investor rates. On a block of flats, the difference is routinely five figures.

The two rate cards

An investor buying residential property in England normally pays the additional-property rates — 5% to £125k, 7% to £250k, 10% to £925k, 15% to £1.5m and 17% above. Non-residential rates are a different world: 0% to £150k, 2% to £250k and 5% on everything above. The 6+ dwellings rule lets a qualifying purchase use the second card.

A worked example

A block of six flats bought for £900,000. At residential additional-property rates the SDLT is £80,000. At non-residential rates it’s £34,500 — a saving of £45,500, simply because the six dwellings completed as one transaction. Check your own figures in the SDLT calculator, which applies the rule automatically.

The fine print

The dwellings must be part of one transaction(or linked transactions) — six separate completions don’t qualify. An alternative is Multiple Dwellings Relief-style averaging... which was abolished in 2024 — the 6+ rule is the one that survives, and that’s precisely why blocks and portfolio purchases are structured as single deals. Mixed-use purchases (a shop with flats above) reach the same non-residential rates by a different door. As ever: this is research, not tax advice — confirm the treatment with your solicitor before exchange.

Why it matters for the deal, not just the bill

SDLT is cash in on day one, so the saving drops straight into your return on cash — and in a title-split play it stacks with the split premium: pay block-level SDLT on the way in, refinance against flat-level values on the way out.