Ancillary services contribution factors

The Frequency Performance Payment (FPP) has replaced Causer Pays as of 8 June 2025. As such, the documents on this page will no longer be updated. The last set of Agg Factors from sample period of 23 March 2025 to 20 April 2025 was applicable for settlement period between 11 May 2025 and 7 June 2025. 

Refer to the following sites for information regarding FPP:

One of the features of the ancillary service market is that only the costs for frequency control regulation services are to be allocated in accordance with contribution factors determined for market participants, as set out in clause 3.15.6A of the National Electricity Rules and detailed in the following procedure.

Under the Rules, AEMO must update these contribution factors every four weeks, and publish the factors at least 10 business days prior to them being applied in the market.

The Rules also require AEMO to publish the historical data used to calculate these factors. This historical data is available here on the AEMO web site.

Final factors used in settlements may vary slightly from previously published values due to minor error corrections.

AEMO calculates contribution factors normalised according to region demand. 

Documentation 2025

Documentation 2024

Documentation 2023

Documentation 2022

Documentation 2021

Documentation 2020

Documentation archive

Older archived files

For older documentation please contact the AEMO Information and Support Hub.