Upper Tribunal (Tax): Expert Witness Guide UK

The Upper Tribunal hears appeals from the First-tier Tribunal on points of law, not fresh evidence. Permission to appeal is sought first from the FTT and is almost always granted. Expert evidence at the Upper Tribunal level is typically limited to matters where new expert analysis is specifically permitted by the tribunal.

The Upper Tribunal also exercises a judicial review function in certain tax matters. Landmark decisions such as HMRC v Harte [2026] UKUT have drawn sharp judicial criticism of HMRC's procedural approach, in that case, the Upper Tribunal upheld the FTT's finding that HMRC had incorrectly applied extended time limits in relation to a discovery assessment.

This highlights the importance of challenging HMRC's procedural decisions as well as the substantive tax analysis. Tax expert witnesses must be familiar with relevant appellate decisions and how they apply to the specific facts of each case.