The National Energy System Operator (NESO) has released its latest five-year forecast for Transmission Network Use of System (TNUoS) tariffs, and it’s clear that significant cost increases are on the horizon. 

From April 2026, the revenue NESO requires from TNUoS charges is expected to rise sharply, reflecting the major investment needed to modernise and expand Britain’s electricity grid. 

What are TNUoS charges? 

TNUoS charges are the fees businesses and energy suppliers pay to use the high-voltage transmission network. This infrastructure transports electricity from generators to regional distribution networks across Great Britain.  

These charges help cover the cost of operating, maintaining, and upgrading the National Grid system, ensuring it can handle increasing demand and connect more renewable energy sources. 

For most businesses, TNUoS charges make up around 10% of their total electricity costs, included within the daily standing charge or passed through as a separate line item on energy bills. 

What’s changing — and why? 

NESO’s latest forecast shows that the Fixed Residual standing charge (based on a site’s capacity banding and voltage level) could almost double from 2025/26 to 2026/27, rising from approximately £3.84 billion to £7.52 billion. By 2030/31, this figure is expected to reach £11.75 billion. 

These increases are primarily driven by the large-scale investment required to upgrade the transmission network to support more renewable energy generation and meet the UK’s Net Zero targets. 

Who sets and regulates these charges? 

The charges are set and administered by NESO, which manages the electricity transmission system across Great Britain. 

However, Ofgem — the UK’s energy regulator — oversees the process and approves the revenue that transmission owners can recover through the RIIO-ET3 price control framework. This mechanism funds essential grid upgrades, such as connecting new offshore wind farms and strengthening infrastructure to move clean energy from where it’s generated to where it’s needed most. 

How will this affect businesses? 

While these increases won’t take effect until April 2026, and we still don’t know precise amounts, businesses need to understand the potential impact on their future energy budgets.  

TNUoS charges influence the standing charge. Businesses with higher consumption or larger import capacities (kVa) will feel the most impact. 

What can businesses do to prepare? 

Although TNUoS charges are largely determined by location and connection capacity, there are practical steps businesses can take to limit their exposure and improve energy cost control: 

Review your energy procurement strategy 

Explore the most suitable contract type —fixed or even semi-flexible —to manage future volatility and control non-commodity costs. For example, some suppliers have already accounted for large increases in higher standing charges even though TNUoS charges are yet to be published. It may be beneficial to secure semi-fixed contracts where TNUoS is charged at pass-through cost and hopefully benefit from lower cost from 1st of April 2026, as this will remove high risk premiums.  

Optimise your Maximum Import Capacity (MIC) 

Businesses with half-hourly meters can often reduce charges by lowering their agreed import capacity, provided it still supports operational needs. 

Increase energy efficiency and explore on-site renewables 

Reducing total consumption and generating part of your energy on-site (e.g., through solar PV) can offset higher grid-related costs in the long term. 

Key dates to watch 

By 30th November 2025: Draft 2026/27 TNUoS tariffs to be released 

By 31th January 2026: Final tariffs confirmed 

April 2026: New charges take effect 

How CES can help 

At CES, we work with businesses across the UK to optimise energy procurement, validate invoices, and manage non-commodity costs, such as TNUoS. Our energy consultants can help you assess how these upcoming changes affect your organisation, and identify opportunities to mitigate the impact through strategic energy management. 

Contact our team at [email protected] to discuss how we can help your business stay ahead of these changes.