Australia’s energy regulator has provisionally refused to let Transgrid pass roughly $1.1 billion of cost overruns on the Project EnergyConnect transmission line through to electricity customers. The decision, made public on 1 September 2026, means a large slice of a well documented budget blowout will not, for now, be added to the network charges buried inside household power bills.
It is a technical ruling with a very ordinary consequence. The poles and wires component of your bill did not just get bigger.
What Transgrid asked for
Project EnergyConnect is the high voltage interconnector linking South Australia and New South Wales, built to move power between the two states and firm up the grid as coal generators retire. Transgrid is responsible for the New South Wales side, and ElectraNet handles the South Australian side.
The New South Wales section has cost far more than planned. Reported total project costs now sit at around $3.6 billion, well above the numbers used when the project was originally approved. On 13 February 2026 Transgrid applied to the Australian Energy Regulator to reopen its 2023 to 2028 revenue determination and add roughly $1.14 billion of extra capital expenditure to the amount it is allowed to recover from customers.
Its case was that the overrun came from events outside its control: flooding in 2022 and 2023, COVID-19 disruption, a global spike in labour and materials costs, inflation, and the collapse of a joint venture partner contracted to deliver the works.
Why the regulator said no
Reopening a revenue determination part way through a regulatory period is meant to be exceptional. There are specific tests a network has to satisfy, and the AER’s provisional view is that Transgrid did not satisfy them.
Two findings did the damage. First, the regulator was not satisfied the cost drivers were genuinely unforeseeable in the way the rules require. Second, it said Transgrid had not demonstrated that failing to deliver the project, or materially delaying it, would be likely to materially and adversely affect grid reliability. That second point matters, because the argument that the project was too important to leave unfinished sat near the centre of the application.
Consumer advocates and at least one large retailer had publicly urged the AER to refuse, arguing the reopener rule was never designed to absorb an overspend of this kind.
What it would have meant for bills
Network charges, the cost of the infrastructure that delivers electricity, are typically the single largest component of a residential power bill. Spending added to a network’s regulatory asset base is recovered from customers over decades, so a billion dollar addition is not a single hit. It is a modest annual increment that keeps arriving for a very long time.
Nobody should attach a precise dollars per household figure to this. The amount would have been spread across a very large customer base over many years, and the allocation would depend on later regulatory steps. Directionally, the outcome is a saving against a worse alternative rather than a cut to what you pay today. Your next bill will not fall because of this ruling.
This is not the end of the matter
An important caveat sits behind the headline. Refusing the reopener does not permanently erase the money.
The AER has been clear that its position would not prevent Transgrid from recovering spending later found to be prudent and efficient. The overspend is expected to be examined through an ex post review as part of Transgrid’s next revenue determination, covering 2028 to 2033. At that point the regulator decides how much of it, if any, belongs in the regulatory asset base that customers ultimately fund. The question has been deferred and the burden of proof pushed back onto the network, not closed off.
When a regulator says no to a network business, it usually means not yet, not never.
Why this keeps happening
The underlying tension is not going away. Australia is building a large amount of new transmission to connect renewable generation and replace retiring coal plants, and major infrastructure in a tight labour market routinely lands above budget. Someone absorbs the gap: the shareholders of the network business, or customers through regulated charges. Decisions like this one draw the line between the two.
That is also why the parallel argument about how much networks are allowed to earn draws so much attention. The allowed rate of return, applied to the asset base, sets the biggest line item on your bill. A separate AER process on that question is running now, with a final decision expected in December 2026. We looked at it in our report on the review of network charges now under way.
What households can actually control
None of this is something you can influence directly. The parts of your bill you can move are the retail margin, your usage, and your own generation.
- Compare your retail plan. Offers change constantly and loyalty is rarely rewarded. Energy Made Easy, run by the AER, is the free official comparison service, and Victorian households use Victorian Energy Compare.
- Check your concessions and rebates. State rebate settings shifted through 2026 and eligibility is easy to overlook. Our rundown of where electricity prices sit in 2026 covers what changed.
- Look at whether generation suits your roof. Solar and battery economics vary by state, tariff and usage pattern, so the answer depends on your numbers. This walkthrough of how solar changes a household bill in practice is a reasonable starting point before you collect quotes.
This article is general information only. It is not personal financial, tax or legal advice, and it does not account for your circumstances.
The bottom line
On 1 September 2026 the AER provisionally rejected Transgrid’s attempt to add roughly $1.1 billion of Project EnergyConnect cost overruns to what it recovers from electricity customers, finding the reopener tests were not met and grid reliability was not credibly at risk. That is a win for households, but a defensive one: it prevents an increase rather than delivering a reduction, and the overspend can still be assessed in the 2028 to 2033 revenue determination.
For the primary source, the AER publishes the application, submissions and determinations on its Transgrid 2023 to 2028 determination page at aer.gov.au. Figures here reflect reporting as at 2 September 2026 and may be revised as the process runs.