This review is about enhancing transparency and future-proofing transmission prices for the future as Aotearoa New Zealand becomes increasingly electrified.
Purpose of the review
The TPM determines how Transpower recovers the annual cost of running the national electricity grid from our transmission customers.
We want to make sure the TPM continues to meet its intended objectives and that customers can easily understand and manage their transmission charges.
Since the Authority introduced the new TPM in 2023, we’ve listened to feedback from customers and investors about how it could work better, particularly around reducing uncertainty, volatility, and complexity.
The operational review aims to improve the operation of the TPM, addressing potential issues identified by stakeholders and Transpower since the implementation of the TPM.
Key Objectives
- Refine adjustment mechanisms to reduce volatility and customer disruption.
- Reconsider the delineation between the simple and standard methods for calculating Benefit-Based Charges (BBCs).
- Improve BBC calculations and inputs to reduce complexity and reliance on judgement, enabling stakeholders to replicate and forecast charges with confidence.
- Ensure First Mover Disadvantage and Prudent Discount provisions remain fit for purpose in an evolving electrification landscape.
These changes aim to support stable, efficient pricing and help New Zealand transition to a low-emissions economy.
Operational Review's four workstreams
| Workstream | Focus area | Submission to the Electricity Authority |
| One | Adjustment events Prudent Discounts First Mover Disadvantage Enabling Code changes | March/April 2026 |
| Two | BBCs: Simple Method review | December 2026 |
| Three | BBCs: Standard Method review | December 2026 |
| Four | Regulatory alignment and any remaining issues identified in previous workstreams | TBD |
High level timeline to April 2026
| Event | Date |
| Invite applications for TPM Operational Review Working Group members | 10 December 2025 |
| Applications for membership to the TPM Operational Review Working Group close | 16 January 2026 |
| Announce TPM Operational Review Working Group members | Late January 2026 |
| Online meeting 1: 2-hour discussion | Early February 2026 |
| Online meeting 2: 2-hour discussion | Mid-February 2026 |
| Transpower publishes workstream 1 for industry comment | Early March 2026 |
| Written submissions close & Transpower publishes responses to submissions | Mid-March 2026 |
| Transpower submits Code change proposals for workstream 1 to the Authority for consideration | April 2026 |
Join the TPM Operational Review Working Group
Transpower is seeking nominations for the Transmission Pricing Methodology (TPM) Operational Review Working Group.
This group will provide expert input into our review of the TPM, helping to refine the methodology and reduce complexity, uncertainty and volatility while supporting efficient transmission pricing.
Applications open 10 December 2025 and close 16 January 2026.
About the role
- Up to 12 members appointed as subject matter experts.
- Contribute in a personal capacity, not as an organisational representative.
- Commitment: Around one day per month for meetings, pre-reading and document review.
- Term: Until January 2027.
- Membership is voluntary; reasonable expenses reimbursed.
Why participate?
Your insights will help shape improvements to the TPM that support stable pricing and New Zealand’s transition to a low-emissions economy.
Click here to read the TPM Operational Review Working Group Terms of Reference.
- What we’ve done so far
Earlier in 2025, we worked with Concept Consulting to complete a two-stage Post-Implementation Review (PIR) of the TPM.
The PIR gave us valuable insights into how well the TPM is meeting its intended objectives, what’s working and where improvements could be made.
The review included:
- Stage 1: An online survey of stakeholders, including electricity distribution businesses, grid-connected customers, and electricity generators.
- Stage 2: Workshops to explore the key themes and ideas raised in the survey.
More information
For more information about the operational review, please contact us at [email protected].
You can find more information about the TPM here on our website.
The TPM itself is available on the Authority’s website.