The shear complexity and amount of change in the SDLT legislation have combined to make the SDLT one of the least-understood taxes levied in the UK, and in particular by those charged to calculate it, namely buyers and their solicitors, who are most often have the task of completing the SDLT return on behalf of their clients.
In addition HMRC’s very own SDLT calculators, on their .gov websites, are not tailored to take account of the many variables which may affect the amount of SDLT due on a transaction.
In-fact, in 2018 HMRC were forced to clarify to a national newspaper reporting on these tax calculators, "that the calculators are intended merely as a guide".
All this means that SDLT calculation mistakes are common – as many as 20% SDLT returns may be incorrectly calculated, leading to millions of pounds overpaid SDLT every year to HMRC every year. This can be because of missed reliefs due to the circumstances of the buyer, incorrect classification of the property type being bought or any one of the more than thirty exemptions within the legislation being missed by a solicitor when completing the SDLT return.