During the Autumn budget, the government announced the introduction of a ‘Mansion Tax’ on homes worth £2m or more. Our analysis shows the number of homes worth £2m+ in England has been steadily falling, a fall which has accelerated since October 2025.
Hamptons has built an Automated Valuation Model (AVM) which re-values every property which has been sold at least once since 1995 every month. It is likely that the VOA (Valuation Office Agency) will do something similar when they come to identify which homes to send bills out to.
Using a local house price index, this model tracks how the number of homes worth £2m+ changes over time, even when a home hasn’t been sold for many years.
Our analysis suggests that there are 8,798 fewer £2m+ homes in England since the concept of a Mansion Tax was introduced in the Autumn Budget. In 2026, the number of £2m+ homes has been falling by 1,000 to 1,500 per month.
The fall in the number of £2m+ homes is likely to mean the Mansion Tax will raise around £28m less per year than it would have in October 2025. Or around £50m a year less than if it was introduced in 2022 when the number of homes worth £2m+ peaked nationally.
Since 2022 however, falling prices, initially in Prime Central London, but then also across Greater London and the South of England, means there are 17,421 fewer £2m+ homes nationally. A 23% fall in Prime Central London numbers have not been offset by increases elsewhere.
Falling values in Prime Central London have also started to move the mansion tax burden geographically. Since the budget, the number of £2m+ properties in PCL has fallen below the numbers in the South East of England.
Given that homes will only be re-assessed for the Mansion Tax every five years, the tax has already started to shape buying behaviour. And in turn these purchases will eventually shape the value of homes which haven't been sold around the thresholds when they come to be valued either for the first time or later on down the line.
