Wholesale Tariff Simplification Sub-group
Chair - James Lancaster (Thames Water)
Purpose
To investigate how to simplify the existing primary tariff structure in the business retail market.
The sub-group aims to impact the market by encouraging and enabling wholesalers to align their tariff structures to the best practice that is agreed collectively by market participants.
Success will be measured by the degree of wholesaler adherence to published Good Practice Guides as well as feedback from market participants, in particular retailers and business customers.
Objectives/Outputs
- Publish metered tariffs Good Practice Guide
- Publish findings from Trade Effluent RFI
- Publish Business Assessed and RV consultation
Assessed Charges consultation
On 24 March the sub-group issued a consultation to seek industry views on options being considered by the sub-group in relation to simplifying and standardising wholesalers' assessed and unmetered (RV based) charges for business retail market properties.
The consultation summary of responses and next steps were published on 22 July 2025.
2025/26 wholesale price rises
In February 2025 the sub-group issued a request to wholesalers to provide retailers and their customers with more information on the 2025/26 wholesale price rises. You can find more information on this request below:
Simplification and harmonisation of metered consumption bands Good Practice Guide
In February 2025 the sub-group published a good practice guide on metered tariff structures. This guide is a result of a phased consultation in 2023 that sought feedback on several options on metered tariff structures. Following refinement of the preferred options, the sub-group recommends that volumetric consumption bands are aligned to a 'Tariff basket structure' with set thresholds, commencing from 1 April 2026.
As set out in the Good Practice Guide, the phased implementation of the recommended metered tariff structure should be completed by the start of the 2030/31 charging year. To assist with commencing the phased implementation from the 2026/27 charging year, CMOS now has the ability to future date tariff transactions, a change introduced in the December 2024 CMOS release.