An investigation of the role which the Ombudsman plays in tax law, on which comparatively little has been written, reveals that the body makes an important and distinct contribution. There is now almost universal acceptance that tax law is overly complex and indeterminate. If the primary law offers few answers to the taxpayer, then HMRC’s role as administrator of the system becomes apparent. Soft law elaborating upon how HMRC will apply the primary law to a given class of taxpayers is rendered indispensable. In practice however, HMRC soft law has often been found to be deficient. Analysis of the current oversight arrangements for HMRC soft law immediately reveals the genesis of these issues. Select committees exercise Parliamentary control, whilst an independent body performs external audits. These entities however only incommensurately examine the soft law. Into this void steps the Parliamentary and Health Service Ombudsman, a body which has ‘carved for itself a distinctive niche’ in the public law framework. The paper accordingly seeks to elaborate upon the important role that the Ombudsman plays in scrutinising HMRC soft law and the lessons which can be derived from this analysis.