Must goods transiting in the EU be reported under CBAM?
No. If goods are declared for temporary admission, for example under Article 95 of Council regulation (EC) No 1186/2009, they do not fall under the scope of the CBAM. Only goods released for free circulation into the EU are subject to the CBAM.
Similarly, the CBAM does not apply in respect to samples of non-EU origin (e.g. sent for testing), which are declared for temporary admission and not released for free circulation.
Source: EC’s Questions and Answers on CBAM