TNUoS Charges Nearly Double from April 2026. Here's What RIIO-3 Means for Your Bill.
Insights
Data Analyst
TNUoS fixed charges rise 40-80% for most businesses from 1 April 2026. A typical small business will pay around £500 more per year.
From 1 April 2026, transmission charges are getting significantly more expensive. TNUoS fixed charges rise 40-80% for most businesses under the new RIIO-3 price control. For a typical small business, that's an extra £500/year.
What's Changing
The TDR (Transmission Demand Residual) is a fixed annual charge based on your connection type — it doesn't scale with how much electricity you use. Here's what businesses will pay from April:
Source: NESO published TNUoS tariff tables. Annual fixed charges by TDR band.
These are fixed annual charges — a site using 50,000 kWh pays the same TDR as one using 1,000,000 kWh if they're in the same band.
Band Thresholds Are Changing
RIIO-3 also shifts the band boundaries. The LV Band 1 threshold rises from 80 kVA to 90 kVA. If your site's capacity is between 80-90 kVA, you might drop into a lower band automatically — saving over £2,100/year.
Our band optimisation feature flags these opportunities when you run a calculation.
Why Is This Happening?
RIIO-3 is Ofgem's new price control period for transmission, running April 2026 to March 2031. The step-change reflects investment in grid reinforcement for renewables and electrification.
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