Before you boil a kettle, run a heater or charge a phone, your electricity account is already costing you money. The daily supply charge ticks over every day of the billing period, empty house or full, and for low-usage homes it can quietly be the biggest line on the bill. It is also the charge people most often ignore when comparing plans, which is exactly why it deserves its own guide.
What the supply charge is
The supply charge (also called a service charge, service to property charge or daily charge) is a fixed amount, usually quoted in cents per day, for being connected to the network. It covers the poles, wires, meters and the retailer's costs of keeping your account alive, and it is charged regardless of how much electricity you use.
A supply charge of 110 cents a day is about $402 a year. At 140 cents it is about $511. That gap of over $100 a year exists before a single kilowatt-hour is bought, which is why two plans with identical usage rates can produce very different bills.
Why supply charges differ so much
Two forces set the spread. The first is the network: it costs more per customer to run wires through sparse country areas than dense suburbs, so regional network areas generally carry higher supply charges than city ones. That part follows your address, and no retailer choice changes it much.
The second is plan design, and this one you can shop. Retailers decide how to split their pricing between the fixed daily charge and the per-kWh rate. Some plans court big households with a higher supply charge and cheaper usage rates; others court apartments with the reverse. Neither design is a trick by itself, but marketing tends to shout the usage rate and whisper the supply charge.
The trade-off, made concrete
Consider two plans. Plan A: 90 cents a day supply, 32 cents per kWh. Plan B: 130 cents a day supply, 27 cents per kWh.
- A low-usage apartment on 8 kWh a day: Plan A costs 90 + (8 × 32) = about $3.46 a day. Plan B costs 130 + (8 × 27) = about $3.46 a day. Dead heat.
- A family home on 20 kWh a day: Plan A costs 90 + (20 × 32) = about $7.30 a day. Plan B costs 130 + (20 × 27) = about $6.70 a day. Plan B wins by roughly $219 a year.
Same two plans, opposite answers depending on nothing but your usage. Below that break-even point the low-supply plan wins, above it the low-rate plan wins, and the only way to know your side of the line is to do the maths with your own daily kWh.
What this means when you compare
- Never rank plans by usage rate alone. The supply charge can erase a rate advantage, especially under about 10 kWh a day.
- Know your daily usage. It is on your bill, and our bill reading guide shows where; if you want to know how yours compares to similar homes, see our average usage guide.
- Low-usage homes should watch the supply charge hardest. Holiday homes, single-person apartments and solar-heavy homes that import little all live or die on the daily charge.
- Do whole-bill maths. Supply plus usage, on your numbers, for every plan.
That last step is exactly what our free calculator does: enter your usage once and it prices every retailer you add per day, month and year, supply charge included. Pick your State, and in Queensland, New South Wales, Victoria, South Australia, Tasmania and the ACT you can import real plans for your postcode from government data.
One caveat to keep expectations honest: you cannot escape supply charges entirely, and a plan advertising an unusually low one has recovered the money somewhere else. The point is not to find the lowest supply charge; it is to find the split that fits your usage. The calculator makes that visible in one table, which beats squinting at two numbers per plan and guessing.