This article discusses the reporting obligations that have been introduced in the European Union for the Carbon Border Adjustment Mechanism (CBAM). Although CBAM goods imported into the European Union will not actually be subjected to a carbon levy until 1 January 2026, a transitional period has entered into effect per 1 October 2023 in which importers of CBAM goods are required to report on a quarterly basis data regarding greenhouse gas emissions that are considered embedded in their imported products. This article discusses not only the data that must be collected and how this data must be reported, but also formal aspects of the reporting process.