This document specifies requirements and guidelines for the quantification and reporting of the process carbon footprint of biobased plastics (see ISO 22526-1), being a partial carbon footprint of a bioplastic product, based on ISO 14067 and consistent with International Standards on life cycle assessment (ISO 14040 and ISO 14044). This document is applicable to process carbon footprint studies (P-CFP) of plastic materials, being a partial carbon footprint of a product, whether or not the results are intended to be publicly available. Requirements and guidelines for the quantification of a partial carbon footprint of a product (partial CFP) are provided in this document. The process carbon footprint study is carried out according to ISO 14067 as a partial carbon footprint, using the specific conditions and requirements specified in this document. Where the results of a P-CFP study are reported according to this document, procedures are provided to support transparency and credibility, and also to allow for informed choices. Offsetting is outside of the scope of this document.