We are considering buying the flat above ours in Coventry and then joining them to make one large duplex flat. Would we be able to reclaim the additional stamp duty land tax charge (i.e. the extra 3% we would be paying for a second purchase)? 

Arthur Weller replies:  

If you look at HMRC’s Stamp Duty Land Tax manual at SDLTM09810 (at Example 9) you will see that in HMRC’s view, this is considered to be the purchase of a second dwelling, and this is not a replacement of the main residence. A refund cannot be claimed once the two properties are merged because the original residence is still owned, albeit in an altered form.