TNUoS Charges Explained: How They’re Calculated, Bands and Business Cost Impact
Transmission Network Use of System (TNUoS) charges are a non-commodity cost included in all UK business electricity bills. They cover the cost of operating, maintaining and developing the high-voltage transmission network that carries electricity from generation sites across the UK to regional distribution networks.
For most businesses, TNUoS makes up around 5-10% of total electricity costs. It sits alongside wholesale unit rates and other network charges within your overall electricity contract.
These charges are now coming into sharper focus. The UK is entering a period of substantial grid investment to support new renewable generation, strengthen infrastructure and improve long-term system resilience. The cost of that investment is recovered through network charging mechanisms such as TNUoS.
From April 2026, many businesses are expected to see an increase in the fixed standing charge element of their electricity bills. This means a greater proportion of your total cost will sit outside direct consumption. Reducing usage alone may not be enough to manage overall spend.
This guide provides a high-level overview of how TNUoS charges work, how the banding system affects businesses and what the upcoming increases could mean for financial planning. Understanding the structure behind these electricity costs will help you build a more informed and resilient energy strategy.
How are TNUoS charges calculated?
The main purpose of TNUoS charges is to recover the revenue approved by Ofgem, the UK’s energy regulator. That revenue funds the licensed transmission operators who run and maintain the high-voltage electricity network across the UK.
The total allowed revenue is split between generators and demand users. Electricity generators contribute around 25% of the total. Homes and businesses, through their suppliers, cover the remaining 75%. Energy suppliers are billed directly for these charges and then pass the cost on through business electricity bills.
TNUoS tariffs are made up of two core elements.
Locational tariffs
Locational tariffs, often referred to as wider TNUoS, reflect the cost of moving electricity to and from different areas of the National Grid. The UK is divided into 27 charging zones, and each zone carries a different rate.
The charge depends on how much strain a site’s location places on the transmission network. Sites located further from major sources of generation, or in areas that require additional reinforcement, can face higher locational charges than those in lower-cost zones.
For businesses operating across multiple sites, this means electricity network costs can vary by region, even where usage levels are similar.
Residual tariffs
Residual tariffs are designed to recover the remaining revenue required to meet Ofgem’s total funding allowance for the transmission system.
Following Ofgem’s Targeted Charging Review (TCR), this element has moved increasingly towards a fixed daily standing charge. Rather than being driven by consumption, it is now largely based on a site’s connection voltage and agreed supply capacity.
This change reduces the link between how much electricity you use and how much you pay in residual TNUoS charges. As a result, a greater proportion of your electricity bill can sit in fixed costs.
Understanding TNUoS charging bands
The residual component of TNUoS charges is applied to business electricity bills based on a banding system established during the TCR. Each commercial meter is allocated to a specific band, which determines the fixed daily charge it will incur. Placement within these bands is primarily determined by a site’s connection voltage level and its agreed capacity, measured in kilovolt-amps (kVA).
The TNUoS bands are typically categorised as follows:
- Connection voltage: meters are classified based on whether they connect at Low Voltage, High Voltage or Extra High Voltage.
- Meter type and capacity: within each voltage level, there are further bands for Non-half hourly and half-hourly meters. For half-hourly metered sites, the specific band is set by the agreed supply capacity. These bands are usually numbered, for example, from 1 to 4, with higher bands corresponding to higher capacities.
A site with a high voltage connection and a large agreed capacity will be placed in a higher band, resulting in a significantly larger fixed daily TNUoS charge. The banding thresholds are set by the National Energy System Operator (NESO) and are subject to change. Updated thresholds are due from April 2026. This may move some sites into higher charging bands, even if their operational needs have not changed.
The business cost impact of rising TNUoS charges
TNUoS charges increases are linked to large-scale investment in the electricity transmission network, required to connect new offshore wind farms and other renewable generation to the National Grid.
From April 2026, the RIIO-ET3 price control period begins. This framework sets the revenue transmission operators are allowed to recover. As a result, total TNUoS revenue is forecast to increase from around £5.1 billion in 2025/26 to approximately £8.9 billion in 2026/27. Further growth is expected, with projections reaching £13.6 billion by 2030/31.
These increases will feed directly into business energy bills through higher network charges.
Key financial impacts for businesses include:
- A rise in fixed daily standing charges: a larger proportion of TNUoS will sit within residual charges, applied as a fixed per-meter, per-day cost. This creates an overhead that does not reduce when electricity consumption falls. Even if usage remains stable or declines, standing charges can continue to rise.
- Reduced impact from consumption management: energy efficiency measures and demand reduction still lower wholesale and commodity costs. However, they will not reduce exposure to fixed TNUoS residual charges. As more cost shifts into standing charges, the link between consumption and total spend weakens.
- Greater pressure on multi-site and energy-intensive businesses: businesses operating large sites or multiple premises will see fixed charges accumulate across each supply point. Energy-intensive sectors such as manufacturing, hospitality and care homes may feel the combined effect more sharply, particularly where electricity demand is continuous.
- Increased contractual exposure: businesses on pass-through electricity contracts will see TNUoS increases reflected directly as tariffs change. Those on fixed agreements may face indirect impact if suppliers have not fully priced future network increases into current rates. In both cases, contract structure influences risk.
- Potential movement into higher charging bands: updated banding thresholds from April 2026 may result in some sites moving into a higher TCR band. This can increase fixed charges further, adding another layer of cost to overall business energy bills.
With network charges rising independently of wholesale market movement, reviewing contract structure and site banding becomes part of forward financial planning. Understanding how these changes flow into your business energy bills will help you budget more accurately and reduce unexpected energy cost increases.
How businesses can mitigate rising TNUoS costs
The move towards higher fixed TNUoS charges creates pressure on operating budgets. While these charges are regulated and unavoidable, there are practical steps businesses can take to manage the financial impact.
A proactive energy strategy helps you stay in control. Reviewing contract structures, checking technical settings and planning ahead of tariff changes can reduce unnecessary exposure.
Key mitigation strategies include:
- Review contracts and banding: start by understanding how TNUoS is treated within your current business electricity contract. In some cases, it is passed through as a separate cost. In others, it may be built into a bundled rate. You should also confirm the TCR band applied to each site. Check that your agreed supply capacity and connection details are accurate, as these influence your charging band and fixed residual costs.
- Optimise agreed capacity (kVA): many businesses hold a higher agreed capacity, measured in kVA, than they actually use. This can place a site in a higher charging band. By analysing your maximum demand and working with your supplier and local distribution network operator, you may be able to reduce your agreed capacity. A lower capacity can mean a lower fixed charge, provided it still supports your operational requirements.
- Invest in on-site generation and storage: on-site generation, such as solar photovoltaic (PV) panels, reduces reliance on grid-supplied electricity. When paired with battery storage, you can store self-generated power and use it during higher demand periods. While fixed residual charges are less consumption-driven than before, reducing overall grid interaction can still support long-term cost control and energy resilience.
- Implement energy efficiency measures: Energy efficiency improvements will not directly reduce fixed TNUoS standing charges. However, they lower total electricity spend and reduce demand on your connection. Over time, sustained reductions in demand can strengthen the case for lowering agreed capacity, which may move your site into a more favourable charging band.
- Stay informed of market changes: NESO typically publishes the TNUoS tariffs by 31 January each year, taking effect from 1 April.
Monitoring these updates allows you to forecast cost changes in advance and factor them into renewal discussions and budget planning.
At Business Utility Hub, we monitor network changes daily and review the full cost structure of your electricity contract - not just the headline unit rate.
How Business Utility Hub can help you manage TNUoS charges
At Business Utility Hub, we look beyond headline unit rates. Our team carries out a detailed review of your business electricity bills to identify your exposure to rising network costs, including TNUoS charges.
We analyse your meter data and site information to check that your current TCR banding and agreed capacity reflect how your business actually operates. If there is a mismatch, we’ll highlight where adjustments could reduce unnecessary fixed charges.
We also compare how different energy suppliers treat non-commodity costs within their electricity contracts. Some agreements pass network charges through directly. Others build them into a fully fixed structure. We explain the financial impact of each approach in plain terms, so you can choose a contract that matches your risk profile and budgeting requirements.
Because we monitor the UK energy market daily, we can assess contract timing alongside upcoming network tariff changes. This helps you avoid reacting after costs rise and instead plan ahead of key implementation dates.
Where appropriate, we support longer-term cost control by:
- Coordinating capacity reviews with your local distribution network operator.
- Reviewing your agreed kVA against actual maximum demand.
- Assessing the commercial case for on-site generation and battery storage.
Our role is to give you a clear view of where costs sit today and how they are likely to move. With the right information, you can control exposure, protect budgets and strengthen your overall energy strategy.
Get clarity on your TNUoS charge exposure
If you would like to understand how upcoming TNUoS charges in 2026 will impact your business electricity bills, call 0800 781 2700 to speak to our team.
Alternatively, email savings@businessutilityhub.co.uk to request a no-obligation contract review.
