Nearly half of outstanding ADR cases using mediators took more than four months to resolve with 222 ADR cases unsettled at this time in 2024-25, accounting for 43% of the total. This was up from just 87 cases the previous year when only in four failed to be sorted within HMRC’s time frame, found analysis by law firm BCLP after an HMRC freedom of information request.

ADR allows more customers to resolve their dispute without the costs and uncertainty involved in a formal tribunal hearing, HMRC said.