This paper revisits barriers to exit, explores their different definitions in the literature and identifies what these have in common. It then analyses the different ways in which such barriers to exit can affect allocative efficiency and competition while assessing their impacts by looking at the effects of barriers to exit on market structure; competitive distortions; and type of entry. Finally, it considers how competition authorities assess barriers to exit in their enforcement and advocacy work to identify differences (or commonalities) of approaches and areas that may warrant further research and discussion. It was prepared as a background note for a discussion held at the OECD in December 2019 on barriers to exit.