The European Chemicals Agency (ECHA) has published a January 2022 update to the Appendix for nanoforms applicable to the Guidance on Registration and Substance Identification (version 2.0). The main changes to the document include additional guidance on the joint submission of data, clarifications regarding the need for one data set per nanoform or set of nanoforms, and information on the registration of sets of nanoforms versus single nanoforms. Changes to the Appendix are limited to Sections 2 and 5 of the currently published document. ECHA intends the document to provide guidance on how to interpret the term “nanoform” for registration purposes and provide advice on how to create “sets of nanoforms” for the purpose of registration. The document outlines what is expected in terms of characterization of the nanoforms and sets of nanoforms in the registration dossier. Finally, the document provides important information related to the joint submission of data on nanoforms, as well as on confidentiality aspects.