Stamp Duty is a tax levied by HM Government on a transfer of property. For residential single property ownership this tax is calculated at 5% for the portion of the property value between £250,001 and £925,000, 10% for the portion between £925,001 and £1,500,000 and 12% for the portion £1,500,001 and over. Duty may also be chargeable on any rental charge (leases only) - this affects both residential and commercial leases where different thresholds are applied. There are different rates for First time buyers and "second homes/buy to let".
See our stamp duty page for more details