EFSA collected data on co‐formulants contained in plant protection product (PPP) formulations for representative uses as part of applications for approval or renewal of active substances, to collate the information available during the peer review process. Information was extracted from pesticide active substances dossiers for which a peer review output was issued between January 2019 and March 2022, in which a total of 182 co‐formulants were found. Most of the data submitted on the identity and physicochemical properties of the co‐formulants are complete as required by Regulation (EU) 284/2013. The data related to (eco)toxicological properties mainly refers to the safety data sheet of the individual co‐formulants and, if available, to registration dossiers under Regulation (EC) 1907/2006 (REACH). Fifty‐three % of the identified co‐formulants have been registered under REACH and about 80% of the 53% are registered for more than 1000 tonnes a year for which registrants are required to submit the most complete data set under REACH. For the remaining percentage, a more limited range of toxicological information is available: EFSA will investigate whether they are exempted from registration under REACH. Co‐formulants contained in plant protection products may also be subject to other European legislation such as the regulations on biocides, food/feed additives, food contact materials, or are included in lists of excipients or cosmetic ingredients. Observations highlighted in the present report can serve Member State risk assessors and risk managers to harmonise the assessment of co‐formulants in collaboration with the EU agencies (EFSA, ECHA).