Stamp duty land tax (SDLT) is a transfer tax that applies to the transfer of land and property within the UK.
Stamp duty is the same whether you are purchasing a house or an empty residential plot for a self build.
The tax threshold increases for non residential land but we would advise extreme caution if you are looking at this type of land for a future self build project. See our land buying section for more information.
At the time of writing SDLT rates and thresholds for residential land and property are as follows:

Source: www.hmrc.gov.uk/sdlt/rates-thresholds.htm#1 (Feb,2010)
Note - The Government temporarily raised the lower threshold to £175,000 on 3 September 2008 in a bid to inflate the punctured housing bubble. The threshold returned to £125,000 on 1 January 2010.
It is the purchaser’s responsibility to notify HMRC of the purchase and to complete a return. Your solicitor or conveyancer should take care of this on your behalf and arrange payment with you.
There are situations where reliefs and exemptions for land and property transactions apply. Have a look on HM Revenue & Customs website for current information about Stamp Duty or discuss it with your conveyancing solicitor.
Look through our self build building costs section for more information on other self build tax issues including capital gains and VAT.