We undertook a review of our approach to how we determine reasonable rates of return for the businesses subject to our regulatory regime. Our review was based on wide-ranging research, regulatory best practice, economic principles and thorough analysis. We also consulted with stakeholders.
We published an updated version of the final paper in September 2024 (version 4). A workbook with an example of a cost of debt calculation is also available after the final report below.
The most recent notice (under ‘Notices’ below) provides more detail of the changes to the report.