From 1 April 2026, non-domestic electricity customers will see significant increases in their Transmission Network Use of System (TNUoS) charges. These are the fees that cover the cost of maintaining and upgrading the UK’s high-voltage transmission network.
The increases are substantial, and they’re causing uncertainty across the sector. Some suppliers are even reopening fixed contracts to pass these costs through to customers.
Here’s what’s happening and what it means for you.
TNUoS charges pay for the UK’s electricity transmission network—the high-voltage infrastructure that moves electricity across the country before it reaches your local distribution network.
These costs are set by the National Energy System Operator (NESO) and regulated by Ofgem. They cover three main things:
Building and maintaining the network. The physical infrastructure that keeps electricity flowing across the UK.
Investment in new infrastructure. Upgrades and expansion needed to meet future energy demand and connect renewable generation.
Regional and usage-based costs. Charges linked to where you are in the country and how you use electricity.
The short answer: major investment in the transmission network.
The UK is undergoing the largest upgrade to its electricity grid in decades. This includes connecting new renewable energy sources (particularly offshore wind), reinforcing the network to handle increasing demand, and ensuring long-term grid stability.
NESO’s forecasts and Ofgem’s determinations show large cost increases for the period 2026–2031. These aren’t supplier decisions—this is a system-wide change driven by national infrastructure investment.
Standing charges will rise. TNUoS charges appear primarily in your standing charges (the fixed daily cost on your electricity bill), not in your unit rates.
The increases vary significantly. How much you’re affected depends on:
This affects all non-domestic customers. From small charities with a single site to large organizations with multiple high-voltage connections—everyone will see increases, though the scale varies widely.
This is where it gets complicated.
Some energy suppliers are reopening fixed-price contracts to add these increased TNUoS charges. This is causing understandable frustration—customers thought they had fixed costs, only to discover that “fixed” doesn’t always cover non-commodity charges like TNUoS.
Here’s what you need to understand:
Many fixed-price contracts only fix the commodity (energy) portion of your bill. Non-commodity charges—like TNUoS, distribution charges, and environmental levies—are often “pass-through” costs that can change when government or regulator decisions change the underlying charges.
This isn’t illegal, but it highlights the importance of understanding your contract terms. If your contract allows suppliers to pass through changes to non-commodity costs, they can reopen it when charges like TNUoS increase significantly.
Look at whether your contract is truly fully fixed or whether it allows pass-through of non-commodity cost changes. If you’re not sure, ask your broker or supplier directly—and get the answer in writing.
Ask your supplier or broker: “What’s the total financial impact of the April 2026 TNUoS increases on our organization?” You need a number, not vague reassurances.
If you’re planning budgets for 2026/27, factor in these increases. The scale varies, but for some customers—particularly those with high voltage or high demand—the impact will be material.
When your next contract comes up for renewal, you’ll face a choice: pay more for a genuinely fully-fixed contract (where the supplier carries the risk of future non-commodity cost changes), or accept a lower rate with pass-through terms (where you carry that risk).
Neither option is inherently better—it depends on your organization’s appetite for risk and your ability to absorb unexpected cost increases.
These TNUoS increases reflect the reality of transforming the UK’s energy system. Connecting renewable generation, reinforcing the grid, and preparing for electrification of heating and transport all require significant investment.
That investment has to be paid for, and non-domestic customers bear a substantial share of transmission costs.
We’re not telling you this is fair or unfair—we’re telling you it’s happening, and you need to be prepared.
We’re monitoring these changes closely and working with customers to understand their specific exposure. If you’re concerned about how the April 2026 increases will affect your organization, get in touch. We’ll review your contracts, clarify your terms, and help you understand what’s coming.
0808 1788 170
heretohelp@utility-aid.co.uk
No fuss. No surprises. Just clear information so you can make informed decisions.
Make an enquiry form
