Discovery has been an issue in the tax system for at least 200 years and it continues to be the subject of considerable case law. At its essence discovery is about certainty: at what point should a person’s tax affairs become final? That simple question does not admit to a straightforward answer. The basic legislative framework as it relates to individuals is set out in TMA 1970 s 29 and there are equivalent provisions for partnerships and companies. The term ‘discovery’ has a wide meaning. However HMRC’s powers to issue discovery assessments are not unfettered. Very broadly a discovery assessment can only be issued if the potential loss of tax was due to careless or deliberate behaviour by the taxpayer; or at the time when an HMRC officer ceased to be entitled to open an enquiry into the return the officer could not reasonably...