Back-Billed for 2 Years of Electricity? The 9-Month Rule (4 Months in Victoria, 12 in Western Australia)

The bill is for $3,412.80 and covers “adjustment: 14 March 2024 to 2 June 2026”. The explanation, when you get one, is that the meter was never read after the smart meter went in, or the account sat in “pending” after you moved, or the wrong tariff was loaded and someone finally noticed. None of it was your doing. You’ve paid every bill they sent. Now they want two years of the difference in 14 days.

The energy rules anticipated exactly this. A retailer that undercharges you because of its own or the distributor’s error can recover the shortfall, but only for a limited period, and only on terms that give you time to pay. In the national framework that period is 9 months. Victoria’s is shorter. Western Australia’s is longer.

Your rights

Under the National Energy Retail Rules (New South Wales, Queensland, South Australia, Tasmania, the Australian Capital Territory):

• The 9-month cap (r 30). Where you’ve been undercharged, the retailer may recover the undercharged amount, but it must not recover any amount relating to a period more than 9 months before you were notified of the undercharging, unless the undercharge was due to your fault or unlawful act (for example, denying meter access or tampering). This limit was introduced by the 2023 rule change; before that it was 9 months in some cases and longer in others, so check the notification date.
• No interest, and time to pay. The retailer can’t charge interest on an undercharged amount, and must offer you a period to pay that is at least as long as the period being back-billed.
• Bills must be based on actual reads where the meter is accessible, and estimated bills must be marked as such. A run of estimates followed by a catch-up is a retailer-side failure, not yours, unless access was refused.
• Bill review and no disconnection (rr 29, 116). You can require a review of the back-bill, and the retailer must not disconnect you for not paying it while the dispute is open with the retailer or the ombudsman.

By state

• New South Wales. NERR r 30: 9 months from notification unless your fault; no interest; payment period at least as long as the back-billed period. Escalation: Energy & Water Ombudsman NSW.
• Victoria. Energy Retail Code of Practice (Essential Services Commission): a retailer must not require payment for undercharging relating to a period more than 4 months before it notified you, unless the undercharge was due to your fault or unlawful act; no interest; a payment period at least equal to the undercharged period. Escalation: Energy and Water Ombudsman (Victoria).
• Queensland. NERR r 30 as above. Escalation: Energy and Water Ombudsman Queensland.
• Western Australia. Code of Conduct for the Supply of Electricity to Small Use Customers 2022: recovery of undercharging is limited to 12 months before notification unless the customer caused it; no interest; the customer must be offered time to pay. Escalation: Energy and Water Ombudsman Western Australia.
• South Australia. NERR r 30 as above. Escalation: Energy and Water Ombudsman SA.
• Tasmania. NERR r 30 applies (Tasmanian modifications don’t remove the back-billing limit). Escalation: Energy Ombudsman Tasmania.
• Australian Capital Territory. NERR r 30 as above. Escalation: ACAT, which acts as the Territory’s energy ombudsman.
• Northern Territory. Outside the national framework. Billing and undercharging are governed by the Electricity Retail Supply Code and the retailer’s customer contract; check the Code’s current undercharging clause rather than assuming a fixed period. Escalation: Ombudsman Northern Territory.

The Claim Done document asks your state first and drafts the dispute to that state’s back-billing rule, with the cap calculated from your notification date.

What to do right now

1. Find the notification date. The cap runs back from the day the retailer first told you, in writing, that you’d been undercharged. It’s usually the date of the adjustment bill or a preceding letter.
2. Count back the cap. 9 months (NERR), 4 months (Victoria), or 12 months (Western Australia). Anything before that date is outside the recoverable period unless the retailer can show you caused the undercharge.
3. Get the read and tariff history. Ask the retailer, in writing, for every meter read (actual and estimated) and every tariff applied for the whole back-billed period, with the calculation of the adjustment. You need it to apportion the amount to inside and outside the cap.
4. Lodge a written dispute. Cite the rule, state the recoverable period, state the amount you accept (if any) and the amount you dispute, require that no interest be applied, require a payment period at least equal to the back-billed period for the accepted amount, and confirm the account is in dispute so disconnection can’t be arranged.
5. Escalate to the ombudsman if the retailer maintains the full amount or doesn’t respond substantively. Back-billing is one of the most common issues ombudsmen resolve, and they apply the rule mechanically.

“Your fault” and what it actually means

The exception for the customer’s fault or unlawful act is narrow and the retailer bears the burden of showing it. Refusing or repeatedly failing to give safe access to a meter, tampering, or connecting without an account are examples. Not noticing that your bills seemed low, not chasing a bill that never came after you moved in, or not querying an estimate are not. Retailers sometimes argue that a customer who “should have known” the bills were too low is at fault; ombudsmen have consistently rejected that. If the retailer relies on the exception, ask it to identify, in writing, the act or omission on your part and the evidence for it. Separately, if the back-bill is for a period before you moved in, that’s not undercharging at all; it’s someone else’s account, and the entire amount is disputed.

Who to complain to

Your retailer first, in writing, with a complaint reference. Then the state energy ombudsman listed above. The Australian Energy Regulator (national framework) or the Essential Services Commission (Victoria) for a systemic breach. If the back-bill is a distributor error (meter data), the retailer is still your point of contact and remains responsible for the bill.

Apply the back-billing cap in writing — $49

Claim Done drafts your Energy Bill Dispute for a back-bill: the rule for your state, the recoverable period calculated from the notification date, the amount disputed, the no-interest and payment-period requirements, the no-disconnection-while-disputed notice, and the ombudsman escalation.

Dispute My Back-Bill — $49 →

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