The standard information requirements for substances are specified in Annexes VI to X and are tonnage-dependent in REACH. As per the new update, Tonnage band changes may be considered during the dossier evaluation process. The registrants will need to prove the volume of their substance especially if they downgrade the tonnage band in their registrations after ECHA has communicated the draft decision to them.

If registrants want ECHA to take a change to their tonnage band into account after they receive a draft dossier evaluation decision, they must communicate the details to the Agency and need to update their dossiers. If they downgrade their tonnage band, they will also need to provide evidence showing the volume of their substance that was imported or manufactured in the last year.

Once the adopted dossier evaluation decision is communicated to registrants, they must fulfill all the required information as outlined in the decision, regardless of tonnage band changes or cease of manufacture that may occur afterward.

Reference: https://echa.europa.eu/-/tonnage-band-changes-may-now-be-taken-into-account-during-dossier-evaluation-process