The Carbon Border Adjustment Mechanism (CBAM) is a key component of the EU Green Deal. Scheduled to transition into operation in January 2023, the CBAM is receiving increasing attention in the media, as well as among researchers, practitioners and policymakers. This note addresses the background to the CBAM, its purpose, its functioning and who will be affected in what way. Finally, the authors comment on whether or not the CBAM is a tax in disguise.