Transpower input methodologies
Input methodologies are the rules, requirements and processes that underpin regulation under Part 4 of the Commerce Act.
Current input methodologies for Transpower
The consolidated Transpower IMs determination below includes the input methodologies that apply for information disclosure regulation and Transpower Individual Price-Quality Path Determination 2025 [2024] NZCC 26. The consolidated Capex IM below incorporates amendments contained in relevant amendment determinations as at 28 April 2026.
The consolidated Transpower IMs determination below includes the amendments to the input methodologies up to the date of consolidation that apply for:
- information disclosure regulation from the commencement of disclosure year 2026; and
- an individual price-quality path that commences on or after 1 April 2025.
Interested persons should use the consolidated version of the principal determination published on 23 April 2024 and clause 5 and Attachment B of the Transpower Input Methodologies (treatment of insurance entitlements) Amendment Determination 2024 [2024] NZCC 39 to identify the input methodologies that apply for:
- information disclosure regulation for disclosure year 2025 and previously; and
- any individual price quality path which commenced before 1 April 2025.
The consolidated Capex IM below includes the amendments to the input methodologies up to the date of consolidation that apply for:
- any individual price-quality path proposal submitted after 14 December 2023;
- any major capital expenditure proposal notified on or after 28 April 2026; and
- an individual price-quality path which commences on or after 1 April 2025.
Interested persons should use the consolidated version of the principal determination published on 23 April 2024 and clause 5 and Attachment B of the Transpower Capital Expenditure Input Methodology (treatment of insurance entitlements) Amendment Determination 2024 [2024] NZCC 40 to identify the input methodologies that apply for:
- information disclosure regulation for disclosure year 2025 and previously;
- an individual price quality path which commenced before 1 April 2025; and
- any major capital expenditure proposal notified before 1 April 2025.
Input methodologies (IMs) are the rules, requirements and processes that underpin regulation under Part 4 of the Commerce Act. We must apply the input methodologies when we set price-quality paths and set information disclosure requirements. Regulated businesses are also required to apply the input methodologies.
There are two IM determinations that apply to Transpower.
The first is generally referred to as the Transpower Input Methodologies Determination (or the Transpower IMs for short). This covers matters such as how assets are to be valued, depreciated and revalued, how we estimate the cost of capital, how tax should be treated, and the allocation of common costs between Transpower's grid operator and system operator services.
The second is generally referred to as the capital expenditure input methodology (or the Capex IM for short). The Capex IM sets out the rules for Transpower proposing, and us assessing, Transpower's capital expenditure proposals.
The purpose of IMs is to promote certainty for suppliers and consumers in relation to the rules, processes and requirements for regulation.
The Transpower IMs were originally determined in 2010, and the Capex IM was originally determined in 2012.
We are required to review the IMs at least every seven years. We substantially completed our first review of the Transpower IMs in 2016, and completed our first review of the Capex IM in 2018. We completed the second review of the Transpower IMs and Capex IM on 13 December 2023. You can find more information about these reviews below.
The reasons for the Transpower IMs and Capex IM are captured in the reasons papers for the original IM determinations and all subsequent amendment determinations – certain determinations and reasons papers can be found via the related pages.