Stamp duty receipts rose by 22% to £14.6 billion in the past 12 months, HMRC data shows.
This represents an increase from £12bn last year, and reflects how investors now have to pay a 5% surcharge on additional properties, up from 3% following last year’s Autumn Budget
Louis Alexander chief executive of specialist lender Somo, said: “Landlords and investors are now contributing far more to stamp duty than before.
“With another Budget only weeks away, there is real uncertainty about what comes next.”
The government is considering reforming the system with fresh property taxes according to reports.
One such idea is replacing stamp duty with an annual property tax charged on homes worth over £500,000, rather than paid upfront at purchase.
Capital gain exemptions could also be introduced on the sale of high-value properties, which would leave investors facing large tax bills when disposing of assets.
Alexander added: “Uncertainty over stamp duty risks paralysing investment.”