This April marks a decade since the introduction of the 3% Stamp Duty surcharge on buy-to-let purchases. George Osborne is now long gone from frontline politics and busy podcasting, AI-ing and a myriad of other things, but the legacy of his policy is still going strong.

The surcharge not only reset the economics of buy-to-let, it marked the end of Government neutrality towards the private rented sector (a market that is a significant contributor to the economy, remember) and it has become a political football ever since.

The surcharge shifted the axis of landlord lending in a way that still defines the market today and created an upfront financial barrier that became too great for many smaller landlords to expand portfolios or for those with an interest to purchase their first property.

One of the greatest impacts was geography. In 2015, ahead of the surcharge, buy-to-let house purchase activity was heavily weighted towards the traditional southern heartlands. The South accounted for nearly 56% of all buy-to-let house purchase volumes, while the Midlands and North combined represented just under 35%.

That pattern reflected a familiar set of assumptions – that capital growth in London and the South East could compensate for tighter yields, and that the ‘safe’ investment case lived largely inside the M25 and its commuter belt.

But when the surcharge landed in April 2016, it injected a new friction into the market, particularly for investors relying on high leverage or acquiring multiple properties. The change did not remove London and the South East from the buy-to-let map. Far from it, they remain among the largest markets and they still attract portfolio landlords who understand the dynamics of mature, high-demand rental locations.

However, the surcharge accelerated an important recalibration. It encouraged landlords to become more commercially focused, and to prioritise affordability, rental demand and sustainable yields over speculative growth.

A decade on, the data shows how lasting that shift has been. By 2025, the regional balance had reversed; the Midlands and North represented just over half of buy-to-let purchase volumes last year, while the South’s share fell to below 40%.

Dig into the detail and the trend becomes even clearer. The North West has emerged as the second largest regional buy-to-let purchase market, accounting for almost 14% of purchase volumes by 2025, up from 9% a decade earlier. Yorkshire has grown to 10% from 7%, and the North East to 7% from 4%.

By contrast, the higher-priced southern regions have seen a structural drop in share following the surcharge and, crucially, that share has not returned to pre-2016 levels. London’s portion of purchase volumes fell from 18% to 12%, the South East declined from 23% to 16%, and the South West from 9% to 6%.

This is where today’s challenge sharpens. Even though London and the South East remain major markets, new purchase transactions in these regions are now less than half of what they were in 2015.

That matters because many parts of the South continue to experience acute pressure from mobility, household formation and constraints on homeownership. If tenant demand meets forecasted levels, the risk is clear – a significant undersupply of private rented homes, feeding further competition and affordability pressures for renters.

For brokers and lenders, the lesson of the past decade is not simply ‘go north’. It’s that buy-to-let has become a more forensic, fundamentals-led market. Landlords are choosing locations where rental yields are resilient, where demand is dependable and where affordability stacks up even when costs rise.

The Stamp Duty surcharge was, undeniably, a defining moment. Ten years on, its legacy is visible in the geography of buy-to-let lending – a rebalanced market, a more commercially disciplined landlord base, and a South that still needs investment, but is receiving far less of it than it once did.

Louisa Sedgwick is managing director of mortgages at Paragon Bank