1 July. That’s the date the Default Market Offer resets every year, whether anyone notices or not. Most households don’t. They see a line on their bill, assume someone in Canberra or Sydney is keeping electricity prices honest, and move on with their week. The honest read is messier than that, and it’s worth fifteen minutes of anyone’s time who’s ever wondered why their neighbour on the same street pays less for the same power.
The Default Market Offer, or DMO, is set annually by the Australian Energy Regulator for three jurisdictions: New South Wales, South Australia, and south-east Queensland. Victoria runs its own version, the Victorian Default Offer, set by the Essential Services Commission rather than the AER. Same idea, different regulator, different postcode. If you’re in Melbourne reading this thinking it doesn’t apply to you, it doesn’t, not directly, though the logic underneath is identical.
Not a price cap, whatever the ads imply #
Here’s the bit that trips people up. The DMO is not a price cap on what retailers can charge.
It’s a reference price and a backstop.
Retailers are free to sell you a market offer above or below it. What they can’t do is charge more than the DMO to a customer sitting on a standing offer, the default contract you land on if you never actively chose a plan. Every bill and every retailer marketing email is legally required to show how a given offer compares to the DMO in dollar terms, which is a decent piece of consumer protection on paper. In practice, a lot of people glance at the comparison, see a modest saving, and don’t bother switching. AGL, Origin and Energy Australia between them still carry a large book of customers who’ve never once changed plans, and standing offers remain the quiet profit centre of the retail business, whatever the public messaging about competition suggests.
How the AER actually builds the number #
The AER doesn’t pluck the DMO out of the air. It uses a building-block model, which sounds dry because it is dry, but it’s the whole ballgame. Network charges, the cost of poles and wires, are usually the single biggest slice of the number, often approaching half the total. Wholesale energy costs come next, and that’s the volatile part, the bit that moves with coal outages, gas prices and how much rooftop solar is flooding the grid at any given hour. Then there’s environmental scheme costs, retail operating costs, and a retail margin the regulator allows on top. Follow the money through those blocks and you can see almost immediately why the number moves the way it does year to year: it isn’t retailer greed setting the pace, it’s the wholesale market and the network businesses behind it.
For readers who want the mechanics of why that wholesale block swings as hard as it does, we’ve covered it in why wholesale electricity prices swing so violently, and the AER publishes the full determination methodology and final decisions on its own site, which is worth a look if you enjoy building-block spreadsheets as much as I apparently do.
Why this year’s reset landed differently #
Wholesale costs have been unusually hard to forecast the last couple of resets, and the reasons aren’t mysterious. Coal capacity has been leaving the grid faster than a lot of network planners expected, a theme we’ve tracked closely in is Australia closing coal faster than it can replace it? and in the long-running saga of Eraring’s extended life. Every time a big, cheap, dispatchable coal unit either closes or has its exit pushed out again, it changes the assumptions sitting inside the DMO’s wholesale cost block for the following year. Add gas supply tightness on the east coast, which we’ve written about more than once, and you get a wholesale forecast that moves around more than anyone at the AER would probably like.
The other moving part is the Capacity Investment Scheme, the federal mechanism underwriting new batteries and renewables to firm up the grid as coal exits. It’s designed to dampen exactly this kind of wholesale volatility over time, though whether it’s working as intended, or quietly picking winners among developers, is a live argument. We’ve made the case on both sides in how the Capacity Investment Scheme actually works and is the Capacity Investment Scheme quietly picking winners?. The scheme is still young. Its fingerprints on the DMO number are there, but faint.
South Australia is the interesting case #
South Australia has always been the outlier jurisdiction in this conversation, mostly because it’s run the hardest on renewables penetration of any state grid in the world, a point we’ve examined at length in South Australia’s renewable energy record: what it hides. High rooftop solar penetration means the wholesale price curve in SA does genuinely strange things at midday, sometimes going negative, a phenomenon we’ve broken down separately in negative electricity prices at midday: what they mean for you. None of that necessarily flows through into a lower DMO for South Australian households, because the building-block model looks at cost recovery across the whole year, not the sunny hour when wholesale prices go negative. It’s a genuine source of frustration for SA consumers who assume all that cheap solar should show up on their bill. It mostly doesn’t, not through this channel anyway.
The switching problem nobody in Canberra wants to own #
Here’s my mildly contrarian bit. I think the DMO, as useful as it is as a consumer safety net, has quietly become an excuse for policymakers to declare the retail market “working” without confronting the fact that a meaningful slice of households still never switch off a standing offer, years after cheaper market offers became freely available. The AEMC’s retail competition reviews have flagged low engagement for years. Comparator sites exist. Retailers are legally required to disclose the gap. And still, inertia wins for a lot of people, especially older customers and those in regional areas with fewer retailer choices to begin with.
The honest read is that a reference price alone doesn’t fix an engagement problem. It just makes the worst-case outcome less bad. That’s not nothing, it’s a genuine consumer protection, but it’s a floor, not a solution.
Where rooftop solar and batteries change the maths #
None of this happens in a vacuum from what’s sitting on your own roof. Feed-in tariffs, set separately by each state’s regulator or, in Victoria’s case, the Essential Services Commission, interact with the DMO in ways that catch people out, particularly households weighing up whether a battery actually pays for itself faster than sticking with a plain solar-plus-grid setup. We’ve run the numbers in how rooftop solar feed-in tariffs actually work in 2026 and again in rooftop solar versus a home battery: which pays back first, and the short version is that the DMO sets your floor on the buy side while the feed-in tariff, a completely separate regulatory instrument, sets what you get on the sell side. The two rarely move in sync, which is exactly why bill shock and bill relief can arrive in the same household in the same year for entirely different reasons.
The bit worth remembering next July #
The DMO will reset again next July, as it has every year since the mechanism was introduced following the ACCC’s 2018 retail electricity pricing inquiry. It’ll move with wholesale costs, network charges and whatever coal capacity has left the grid in the meantime. None of that is under any individual household’s control. What is under your control is whether you’re one of the customers still sitting on a standing offer priced at the DMO ceiling, when a five-minute look at a market offer might save real money. I’ll admit I went years without checking my own plan against the comparator tools, on the reasonable assumption that switching retailers is about as much fun as watching a rain delay at the SCG. It isn’t fun. It’s also not hard, and the gap between the two numbers is usually bigger than people expect.
The AER publishes the current DMO determination and the full building-block breakdown on its website, and it’s genuinely worth ten minutes with a recent power bill open beside it. Most people never make that comparison. That’s the actual story here, not the number itself.
— Marcus Wren, Editor
Photo by Bernd 📷 Dittrich on Unsplash