TNUoS Charges 2026 Explained
What is TNUoS, how are TNUoS charges calculated, and why are they increasing in 2026? Here’s what it means for your business energy costs and what to do next.
Hidden inside your business energy bill is a charge most people have never heard of. TNUoS (Transmission Network Use of System charges) are a component of your electricity costs that pay for the national high-voltage transmission grid. And in April 2026, they're going up significantly.
If your energy contract is coming up for renewal, or if you haven't reviewed your costs recently, this is something you need to understand, especially when assessing your wider business energy strategy and long-term costs.
The national electricity transmission network, the pylons, cables and substations that carry power across the country, is owned and operated by National Grid. Maintaining and investing in that infrastructure costs money, and those costs are passed on to businesses and generators through TNUoS charges.
The meaning of TNUoS is simple in principle: it is the cost of using the UK’s transmission network to move electricity from where it’s generated to where it’s used.
TNUoS charges are set annually by Ofgem and recovered through your electricity supplier. They appear as a component of your unit rate or as a separate line on your invoice, depending on your contract type. Either way, you're paying them, whether you know it or not.
The UK's electricity grid is undergoing significant investment to support the transition to net zero. Connecting new offshore wind capacity, reinforcing transmission infrastructure, and upgrading ageing parts of the network all require capital. That capital is ultimately funded through network charges.
According to NESO, transmission network costs are set to rise sharply, with increases of over 60% confirmed for April 2026. These TNUoS charges increase reflects the scale of infrastructure investment required across the UK energy system.
Ofgem approves the level of charges each year. For TNUoS charges 2026, this means a noticeable uplift in costs across commercial electricity bills. These increases are not optional, and they apply regardless of which supplier you're with.
Understanding how TNUoS charges are calculated helps explain why costs vary between businesses.
TNUoS charges are calculated based on several factors, including:
For larger businesses, especially those on half-hourly meters, charges are often influenced by demand during peak grid usage periods. This means your usage patterns can directly impact how much you pay.
How much will TNUoS charges cost my business?
The impact of TNUoS charges depends on your consumption profile and how your contract is structured. Half-hourly metered businesses (typically those consuming above 100MWh per year) are generally more exposed to network charge pass-throughs. But all commercial electricity customers will feel some impact.
With TNUoS charges in 2026 increasing significantly, businesses that haven’t reviewed their contracts recently may see higher costs than expected. The headline message is clear: for businesses that haven’t locked in a contract ahead of these increases, costs will rise.
Not entirely. TNUoS charges are a regulated cost that every electricity user pays. However, there are ways to manage your exposure and reduce risk:
If your electricity contract expires before or around April 2026, you should be reviewing your options now. Forward contracts already reflect expected TNUoS charges increases, but acting before the formal uplift date gives you more negotiating leverage and access to better options.
If your contract extends beyond April, it’s still important to understand how TNUoS charges are structured within it, particularly if you're currently out of contract or on a variable rate.
The businesses that manage energy costs effectively are those that understand the details. TNUoS charges are just one part of the picture, but right now, they are a significant one.
