2025 Transition Plan for System Security (TPSS)

The Transition Plan for System Security (TPSS) is an annual report focusing on maintaining power system security as the National Electricity Market (NEM) transitions towards lower emissions. It provides a structured approach for the energy sector to navigate key upcoming Transition Points – events that require material changes in the operational approach to managing power system security – over at least the next 10 years.

On 1 December 2025, AEMO released its second TPSS, outlining expected system security needs for each region of the National Electricity Market (NEM) over the coming decade.

This TPSS consolidates four system security reports into a single plan that identifies emerging security gaps, required investments, and collaborative actions. Reporting on NSCAS, system strength, and inertia is now integrated with the TPSS, with specific information for TNSPs contained in a dedicated appendix.

Transition Plan main report breakdown

Part A articulates system security and important understanding to discuss the transition.
Discusses how the energy transition affects system security and AEMO’s transition planning activities.
Most recommended for policy makers and market participants.

Part B presents transition plans for each NEM region, incorporating insights from security planning studies.
Describes upcoming transition points identified by AEMO and highlights key actions to manage them.
Most recommended for market participants, regional TNSPs, regional policy makers and state governments.

Part C describes important detail on priority transmission and distribution level developments and key technologies.
Most recommended for policy makers, market participants and TNSPs.

Transition Plan appendices

Appendix 1 reproduces the April 2025 letter from the Reliability Panel providing feedback on the 2024 Transition Plan for System Security.

Appendix 2 contains NSCAS, system strength and inertia planning requirements for TNSPs.

Appendix 3 contains minimum demand forecasts, current emergency backstop capacity, and forecast incidence of MSL events.

Submissions

AEMO received six non‑confidential submissions in response to the 2025 TPSS consultation, which was open for feedback until 16 February 2026. These submissions are published below. AEMO will publish a consultation overview after considering stakeholder feedback, including the AEMC Reliability Panel’s submission once received.