The 3% additional SDLT charge has applied to the purchase of additional dwellings by individuals and the purchase of first and subsequent dwellings by non-natural persons since 1 April 2016. There is an exception for the replacement of a main residence but there are traps for the unwary. The interaction of the charge with multiple dwellings relief and transactions that are linked needs careful computation of the tax payable. The purchase by trustees of a dwelling also requires careful analysis of the rules.