The key assumptions behind the forecast for expected revenue from the Stamp Duty Land Tax
) higher rates for additional properties are as set out in the Spending Review
and Autumn Statement 2015 and Budget 2016
policy costings. The tax base was estimated by combining price and volumes data from the Council of Mortgage Lenders, Census 2011 and administrative data from SDLT and Council Tax
. The tax base was projected to grow over the forecast period in line with the OBR
Autumn Statement 2015 forecasts for residential SDLT, residential transactions and average house prices. The costing also accounted for a behavioural response. At Budget 2016 the size of the tax base was re-estimated by the OBR using HM Revenue and Customs
administrative data from SDLT returns.