SolvedONSCG9500 | Reviews and appeals: direct tax letters containing appealable decisions
From HM Revenue & Customs · Non-statutory Clearance Guidance
It is unlikely that clearance teams will make appealable direct tax decisions. If you are uncertain about whether a decision you give is appealable you should contact TALA for advice.
If you do make an appealable direct tax decision, full details of the process and standard paragraphs for inclusion are contained in Appeals Reviews and Tribunals Guidance (ARTG).
The letter template for direct taxes can be found at NSCG6350.