An exposure draft of the Tranche 9 proposed amendments was published on 27 October 2025. When developing the exposure draft, additional issues relating to the implementation of the new regime for Demand Side Programmes were identified for which rule changes could not be developed in time to be included in the exposure draft. An addendum including these changes was published separately on 10 November 2025. The consultation period closed on 19 November 2025.
Energy Policy WA (EPWA) held a meeting of the Transformation Design and Operation Working Group (TDOWG) on 12 November 2025 to discuss the Amending Rules.
A summary of EPWA’s response to stakeholder submissions is available here.
Following the publication of the Essential System Services Framework Review – Consultation Paper, EPWA published for consultation an addendum with proposed ESM Amending Rules to increase the Rate of Change of Frequency (RoCoF) Safe Limit from 0.25 Hz per 0.5 seconds to 0.75 Hz per second, to implement one of the proposed outcomes of the Review.
The proposed ESM Amending Rules to relax the RoCoF Safe Limit will reduce unnecessary market intervention by the AEMO and the resulting energy uplift payments, thus reducing costs to consumers. This change was included in the Electricity System and Market Amendment (Tranche 9) Rules 2025 to commence on 26 February 2026.
The Electricity System and Market Amendment (Tranche 9) Rules 2025 also include:
Notice of the making of the Amending Rules was published in the Government Gazette on 23 December 2025.
Schedule 1 will commence at 8:00am on 1 January 2026.