Authority publishes data source assessment for determining the EAF

The Electricity Authority Te Mana Hiko (the Authority) has published an assessment of gas price data that is used to determine the Electricity Allocation Factor (EAF).

The assessment looks at a range of potential data sources that could be used as an input to determine the EAF and evaluates whether they meet the legal and practical requirements the Authority must follow.

After reviewing available alternatives, the Authority has concluded that gas spot price data provided by Energy Market Services (EMS) remains suitable for determining the EAF at this time.

Looking ahead, we note that gas market conditions can be volatile and relying on a single data source may not always provide the strongest signal during periods of market stress. As part of our forward work programme, we will consider whether a composite gas price index could be developed using publicly available data for the 2026/27 EAF determination.

We will also consider whether introducing an additional five-day rolling average during periods of heightened volatility in the gas spot market could improve the reliability of EMS data used to determine the EAF.

An earlier version of the data source assessment was shared with relevant stakeholders, including the Major Electricity Users’ Group, EMS, Genesis, Contact and Nova. Submissions from stakeholders provided valuable feedback on our earlier analysis and the practical implications of potential changes to the EAF methodology. Submissions are published below.

The published assessment supports our commitment to transparency and a robust and reliable EAF. It also provides a clear foundation for further work on the EAF ahead of the 2026/27 financial year.

We expect to publish a determination of the EAF for the 2025/26 financial year in July 2026.

Read assessment