Appeals were allowed against HMRC’s refusal of overpayment relief claims based on top slicing relief calculations, as HMRC had not established the existence of ‘practice generally prevailing’ when the appellants’ tax returns (in respect of the disputed top slicing relief claims) were filed. 

On 11 July 2018, the first appellant (RJ) filed his tax return for 2017/18, which included a ‘top slicing relief’ (TSR) calculation on chargeable event gains. On 5 May 2020, RJ made an overpayment relief claim in respect of TSR and provided an amended TSR calculation showing a higher amount of TSR. However, following a compliance check, HM Revenue and Customs (HMRC) concluded that RJ’s claim contained an incorrect amount of TSR, and refused the refund claimed. RJ appealed on the basis that HMRC’s calculation of TSR did not meet the conditions for constituting ‘practice generally prevailing’ (PGP). HMRC’s