This practice note summarises the development of anti-avoidance case law from WT Ramsay v Inland Revenue Commissioners (1982) 54 TC 101 to date. It includes a selection of decisions of the First-tier and Upper Tribunals, which illustrate the application of the Ramsay principle. It also includes some practical tips for structuring transactions to reduce the risk of attack by HMRC based on anti-avoidance case law.