This document provides guidance to applicants submitting dossiers related to the approval of pesticide active substances and for setting of maximum residue levels, and to Member States preparing assessment reports on active substances within the scope of Regulation (EC) No 1107/2009 and Commission Implementing Regulation (EU) 2020/1740, or evaluation reports on maximum residue levels applications, within the scope of Regulation (EC) No 396/2005. It describes the administrative requirements for the preparation and submission of the dossier to support an application for the approval, the amendment of approval or the renewal of an existing approval of a pesticide active substance, and for maximum residue levels, for applications submitted as of 27 March 2021. It also describes the support initiatives available from the preparation of the application (presubmission phase) to the adoption and publication of EFSA's output. The Transparency Regulation amended the General Food Law by introducing new provisions in the presubmission phase and in the application procedure: general pre-submission advice, specific aspects for intended applications for renewal (notification of intended studies, including their design, public consultation on the intended studies, renewal pre-submission advice by EFSA), notification of information related to studies commissioned or carried out to support an application, public disclosure of non-confidential version of all information submitted in support of the application and related confidentiality decision-making process, public consultation on submitted applications. These new requirements, as implemented by the Practical Arrangements laid down by EFSA, are reflected in this guidance. The guidance describes the procedures and the associated timelines for handling applications related to pesticide active substances. It provides additional instructions and guidance to applicants and rapporteur Member States, and co-rapporteur Member States where relevant, with the aim to enhance the quality of application dossiers and assessment reports. The document also provides guidance to applicants and Evaluating Member States on applications for the setting of maximum residue levels, in particular concerning the provisions introduced by the Transparency Regulation amending the General Food Law and their implementation in the procedure for such applications, according to the Practical Arrangements laid down by EFSA.