Is the CBAM Transitional Registry the same as the EU Customs trader portal?
The CBAM Transitional Registry for reporting declarants runs independently of the EU Customs Trader Portal (EUCTP). However existing importers that will be also acting as CBAM Declarants may be able to use their existing user account if the EU Member State allows it. Depending on the Member State, specific access to the CBAM module may need to be requested.
Source: EC’s Questions and Answers on CBAM