In April 2016 the government added a 3% stamp-duty surcharge on additional residential property. It was meant to cool buy-to-let. What it actually did - alongside Section 24 - was change the structure of who buys, pushing investors toward companies and toward fewer, larger purchases. The clearest record of that shift is not a public statistic but the shape of GalimAI’s own database, where company ownership is now the norm. This study reads the surcharge’s effect from that proprietary map.
What GalimAI’s own data reveals
The surcharge does not sit in GalimAI’s data as a tax line - it sits as a population. The 463,022 property-owning companies GalimAI maps across England and Wales are the structures investors moved into to manage the rising fixed cost of buying additional property: limited companies and SPVs, each linked in our data to the people who control them, what they hold, and how they are financed. Public records can confirm a company exists; GalimAI’s map shows who is behind it and whether it is under strain.
That linkage is the unique part. Our own analyses trace the behaviour the surcharge encouraged - the SPV flipper pattern of buy-improve-sell inside a company wrapper, the new buyer companies formed in 2025, and the owners most active in the last 24 months, who absorb the stock that individual landlords are now selling. The surcharge raised the cost of every additional purchase, so it also concentrated activity into better-capitalised company buyers - exactly the cohort GalimAI surfaces.
For an investor that is the practical payoff: the buyers still active after the surcharge, and the individual owners most likely to sell because the next purchase no longer stacks up, are not a statistic in GalimAI but a reachable list of named owners attached to their property and financing.
What changed: the surcharge, in plain terms
From 1 April 2016 buyers of an additional residential property worth more than £40,000 paid a 3% surcharge on top of standard stamp-duty rates, across the whole price. At the Autumn Budget on 31 October 2024 the surcharge was raised from 3% to 5%, sharpening the same pressure.
Because it applies to the full purchase price of any additional property, the surcharge is a flat entry cost on portfolio growth - paid by individual landlords and companies alike, but felt most by buyers trying to scale. Combined with Section 24, it made the company route the default for serious investors.
The public backdrop
The public signal is the well-documented rise of company-held buy-to-let: limited-company landlords have grown to roughly 400,000 by 2025, with the great majority of new rental purchases now incorporated. That is the same shift GalimAI’s 463,022-company map shows in full - owner by owner, with financing and distress signals attached - rather than as a national headline.
The most plausible mechanism
The surcharge raised the fixed cost of buying additional property, which did two things at once: it pushed investors toward the company structures that pair with Section 24, and it tilted the market toward fewer, better-capitalised buyers. We read this as a strong, well-evidenced correlation with a clear mechanism, not proof that the surcharge alone explains the move to companies - Section 24, stamp-duty bands and lender appetite pushed the same way.
Sources
The proprietary figures in this study (the 463,022 companies, 1,000,000+ owners and the distress signals) are GalimAI first-party data. The public background figures are drawn from:
- HMRC / GOV.UK - Stamp Duty Land Tax rates (higher rates for additional dwellings)
- NRLA - stamp duty changes explained
Frequently asked questions
What does GalimAI's own data add here?
GalimAI maps 463,022 property-owning companies and 1M+ owners across England and Wales - the company-and-SPV market the surcharge and Section 24 made the norm - each linked to directors, holdings, financing and distress signals, so the shift is visible owner by owner.
What is the stamp-duty surcharge on additional property?
A surcharge on buying an additional residential property worth over 40,000 pounds. It was introduced at 3% from April 2016 and raised to 5% on 31 October 2024, charged on top of standard stamp-duty rates across the whole price.
Did it cause the move to company ownership?
It is one of the clearest drivers, alongside Section 24 - a strong correlation with a clear mechanism. Company purchases avoid some of the personal-tax drag, so investors incorporated. Other taxes and lender appetite also contributed.
How can investors use this?
The buyers still active after the surcharge, and individual owners most likely to sell, are a reachable list of named owners in GalimAI.