DUoS charges — Distribution Use of System charges — appear on every business electricity bill in Ireland, and most business owners have no idea what they are or whether they're correct. That's a problem, because being on the wrong DUoS band is one of the most expensive billing errors in the Irish energy market. ESB Networks has historically identified approximately 3,800 connections with incorrect classifications, and a €100.86 million rebalancing error between 2011 and 2022 shows just how systemic the issue is.
If you're a business owner, this is worth understanding. The numbers are significant.
What DUoS charges actually are
DUoS charges fund ESB Networks' distribution infrastructure — the poles, wires, substations, and equipment that deliver electricity from the national grid to your premises. They're regulated by the CRU, reviewed annually, and take effect each October. Every business pays them, and they represent a substantial portion of your total electricity bill.
The charges come in several parts: a standing charge (fixed annual fee), a capacity charge (based on your MIC, for maximum demand customers), and unit rates (per kWh, split into day and night). How much you pay depends entirely on which DUoS group you're assigned to.
The DUoS bands and what they cost
ESB Networks assigns every business connection to a DUoS group based on your voltage level, MIC threshold, and metering type. Here are the key bands for businesses:
DG5 — Low Voltage, Non-Maximum Demand is the most common band for smaller businesses. You pay a standing charge of €141.55 per year, plus unit rates of 7.6 c/kWh during the day and 0.9 c/kWh at night (or 6.5 c/kWh on a 24-hour rate). There's no capacity charge. This band applies to businesses with MIC below 50 kVA. DG6 — Low Voltage, Maximum Demand is for businesses above the 50 kVA MIC threshold. The standing charge jumps to €1,320.36 per year, and you pay a capacity charge of €49.28 per kVA of MIC per year. In exchange, unit rates drop to 3.9 c/kWh day and 0.5 c/kWh night. For a business with 100 kVA MIC, the capacity charge alone is €4,928 per year. DG7 — Medium Voltage connections have a standing charge of €5,161 per year, capacity charges of €37.74 per kVA per year, and unit rates of just 1.5 c/kWh day and 0.2 c/kWh night. This band also carries peak rates and power factor surcharges. DG8 and DG9 cover 38kV connections — large industrial and data centre scale — with standing charges reaching €86,517 per year but unit rates below 0.4 c/kWh.The pattern is clear: higher voltage connections pay more in fixed charges but far less per unit. For high-consumption businesses, this trade-off saves substantial money. For lower-consumption businesses incorrectly classified in a higher band, it costs a fortune.
The 50 kVA threshold: where businesses get caught
The critical dividing line is 50 kVA of MIC. Below it, you're on DG5 with simple pricing. Above it, you're on DG6 with capacity-based charging. Getting this wrong in either direction is expensive.
Scenario 1: You're on DG6 but should be on DG5. Your actual peak demand is well below 50 kVA, but your connection agreement specifies a higher MIC — perhaps inherited from a previous tenant or set during a fit-out that assumed higher loads. You're paying the DG6 standing charge (€1,320 vs €142) and capacity charges you don't need. A business with 100 kVA MIC but actual demand of 40 kVA overpays by roughly €4,100 per year on capacity charges and standing charges combined, plus excess PSO levy. Scenario 2: You're on DG5 but your demand has grown past 50 kVA. ESB Networks may eventually reclassify you, but in the meantime you're paying higher per-unit DUoS rates on all your consumption. For a high-consumption business, the DG5 unit rates (6.5–7.6 c/kWh) versus DG6 (0.5–3.9 c/kWh) add up fast.ESB Networks assigns your DUoS group based on the connection agreement, not your actual usage. If your business has changed since the agreement was set, your band may be wrong.
How businesses end up on the wrong band
There are several common ways this happens:
Inheriting a previous tenant's MIC. When you move into business premises, the existing MIC and DUoS classification carry over unless you actively request a change. The previous occupant may have needed 150 kVA; your business might need 30 kVA. But you'll keep paying for 150 kVA until you submit an NC3 form to ESB Networks. Downsizing without updating. If your business has reduced operations, removed equipment, or shifted to more efficient technology, your actual demand may have dropped well below your registered MIC. Unless you request a review, the old setting — and its charges — persist indefinitely. Original over-specification. Electrical contractors sometimes specify higher MIC during fit-out to provide headroom. That conservatism becomes an ongoing cost if the actual demand never materialises. Incorrect reclassification. ESB Networks processes thousands of connections, and errors happen. The €100.86 million Large Energy User rebalancing error — where domestic customers were overcharged over an 11-year period due to DUoS misallocation — shows the scale at which classification errors can occur.How to check your DUoS band
Your DUoS group (DG number) appears on your electricity bill. Find it and check it against your actual connection. Then ask:
- Is my MIC set correctly for my current peak demand?
- Am I on DG5 or DG6, and does that match my MIC?
- If I'm on DG6, is my MIC the right size, or am I paying for unused capacity?
What to do if you're on the wrong band
If you discover you've been overcharged due to an incorrect DUoS classification or oversized MIC, you may be entitled to a refund. The amount depends on how long the error has been in place and how significant the overcharge is, but for MIC and DUoS issues, back-payments of several thousand euros are not uncommon.
Send us your bill and we'll check your DUoS band, MIC setting, and capacity charges for free. If something's wrong, we'll handle the correction and pursue any refund you're owed.