Sole proprietorships remain responsible for assessing their responsibilities and carrying out the registration. Members of a SIEF may also use a consortium to ensure, for example, the legal protection of their interests. We ask you to sign the SIEF agreement before February 1, 2018, if you intend to register in 2018. If your company has a 2018 registration deadline but would like to register earlier, please contact firstname.lastname@example.org immediately to discuss the agreements. The integration of a SIEF is mandatory for all agents of the substance to exchange data. Participation in a consortium may be useful for some Lead Registrants, but it is not mandatory. See the article on the difference between member and lead filers. The law firm Keller & Heckman LLP is the custodian of the agreement.