GST applies to almost all consumer items in Australia, including energy bills. But unfortunately, for long-suffering energy consumers, the GST element in energy bills is far from straightforward and can lead to confusion when comparing bills and plans.

This article explains how GST works for energy bills and describes how Bill Hero handles GST calculations.

Every retailer is obliged to quote GST-inclusive pricing in their fact sheets and offers - so every time you see details for a new plan offered by any retailer, you can be confident that the quoted rates and pricing will already include GST.

Solar feed-in tariff rates are not subject to GST, so the solar FiT rates quoted in the retailer Fact Sheet and in your solar bills will always be displayed as GST-exclusive amounts.

Although retailers are obliged to quote inc-GST pricing in their fact sheets, many retailers issue bills that display ex-GST rates for the various line items documented in the bill.

This can make it tricky to compare your current rates vs the rates offered under an alternative plan - the rates for the new plan will always be quoted inc-GST, but your current bill may or may not display inc-GST rates, so it's not always possible to compare the rates per kWh in your bill vs an alternative Fact Sheet.

AGL is a particular offender in this regard, but many other retailer bills also display non-GST rates.

In principle, GST should be quite simple in energy bills - a 10% GST uplift applies to every line item except for solar FiT, which, as we've seen, is GST-free.

However, in practice, bills can get complicated with the application of incentives, discounts and other price-impacting elements, and retailers can be inconsistent in how GST is applied to these elements in their bills.

For example, some retailer bills will display ex-GST rates for kWh consumption but will include GST in concessions or discount amounts. Others will do the opposite with inc-GST consumption rates and ex-GST concessions and discounts.

You may need to look very closely at your bill to determine if the rates are displayed, including or excluding GST.

Some retailers make it easy by stating the rates are inclusive of GST. For example, this extract from a Momentum Energy bill clearly displays that the pricing is 'GST incl':

Others are less obvious, but you can still tell that it's GST inclusive. For example, this Origin Energy bill does not disclose in the line items if the pricing is inc-or ex-GST:

However, if you look at the final total for this bill, it reveals that all the pricing is inc-GST:

Here's an example from AGL where the GST status is similarly not revealed for each line item:

Only by looking at the final total can we determine that all the rates in this bill are displayed excluding GST, and because of this, the final bill price is 10% higher than what you'd expect by looking at the line items individually:
​

Bill Hero's core analysis is to calculate what the consumption documented in your current bill would have cost you under each of the relevant alternative plans available to you.

Those alternative plans are always quoted with inc-GST rates, so Bill Hero calculates a GST-inclusive Comparison Price for your uploaded bill, even if your bill happens to be a GST-exclusive bill.