The European Chemicals Agency (ECHA) expects to launch a call for tenders late June/early July 2026, with a deadline to submit offer in September 2026, for the project “Nanomaterial Risk Assessment: Refining and Validating Acceptable Variation in Nanoform Characterisers” The project is meant to follow up to on previous project “Nanomaterial Risk Assessment: A regulatory way forward for sameness and grouping approaches”1 contracted in 2023. In the previous contract, a framework was developed to assess the acceptable variation within each characteriser of a Nanoform (as per Section 2.4 of Annex VI of REACH Regulation). The project aimed at exploring ways to simplify nanoforms registration process and, ultimately, its’ associated testing burden. As an outcome, a series of binary decision trees and respective variability threshold were produced, covering each mandatory characteriser. The framework was developed based on a limited set of information covering metallic and carbon-based nanomaterials. The final report as well as the Decision Tree can be found here: https://echa.europa.eu/fi/science/publications-and-reports/reports, so that interested parties can already familiarize themselves with the outcome of the project. The new contract aims at refining the threshold values pre-established and validating it with additional data sets, covering a wider range of chemical types. The project outcome is expected to become a basis for ECHA to develop new guidance for registrants of nanoforms of a substance.