Companies need to clearly identify the substances they manufacture or import. This makes it possible for companies to register the same substance jointly, following the ‘one substance, one registration’ principle under REACH.

Be clear on what you register – lead registrant

• Report the boundary composition for the registered substance, including constituents or groups of constituents, impurities and additives, as well as their concentrations, on behalf of all member registrants. If a large variation of compositions exists, or if compositions have different classifications, you should report more than one boundary composition.
• Report your legal entity composition ensuring that it is within the boundary composition.
• Provide test material information under each endpoint study record in IUCLID.
• Report information on test materials on behalf of all member registrants. Identities of the constituents or groups of constituents, impurities and additives, as well as their concentration values for each test material used to generate the data for information requirements listed in REACH Annexes VII-XI must be included. The reporting of the test material composition should follow the same rules as the composition reporting of the registered substance.
• Report all the characterisation parameters specific for nanoforms or sets of similar nanoforms if you register nanoforms of a substance.

Be clear on what you register – only registrant

• The same advice as for the lead registrant applies if you are the only registrant for your substance.

Be clear on what you register – member of a joint submission

• As a member of a joint submission, make sure that the legal entity composition for your substance is within the boundary composition reported in the lead registrant dossier.