TL;DR: On today’s Brisbane metro median of 175.9 c/L, the government’s total cut is 52.6 c/L — 36.6 c excise plus 16.0 c GST — which, by coincidence, equals the full excise rate that returns in August. That total is 29.9 percent of the pump price today, not 40. The excise is on relief until 1 August; when the full 52.6 c excise rate returns, the same litre becomes 39.0 percent tax. Even then it is highest when fuel is cheapest.
The question. You have heard it at the servo counter and in the group chat: “40% of the price of petrol goes to the govt.” It is a widely-repeated line — one version, on r/australia, runs “40% of he price of petrol goes to the govt.” It gets repeated because it is close enough to feel true. So is it right?
What we checked. Two of the three numbers here are not ours to move. The federal fuel excise is a flat per-litre charge — an ATO rate, the same whether petrol is dear or cheap. Right now it sits at 36.6 c because of the relief measure that runs until 1 August; the full indexed rate is 52.6 c. GST is one eleventh of the pump price you actually pay. The third number, the pump price, is the one we serve: the live QLD Government feed. So we took today’s Brisbane metro median ULP price across 440 stations — 175.9 c/L — and did the sum: (excise + price ÷ 11) ÷ price.
What the data shows. At 175.9 c/L today, excise is 36.6 c and GST is 16.0 c. Together that is 52.6 c of tax in every litre, which is 29.9 percent. Well under the folk 40.
That number does not stay put, and for two reasons. The first is on the calendar: on 1 August the relief ends and the excise steps back to 52.6 c. On the same 175.9 c/L, that lifts the tax share to 39.0 percent — the folk figure is a fortnight away, not here today.
The second reason is subtler, and it holds in either world: the share moves the opposite way to what you would guess. Excise is flat, so only the GST scales with price, and the tax percentage falls as the pump price rises. Take the full 52.6 c rate that returns in August. At the cheap end of the cycle — a daily median around 159.9 c/L — tax would be 67.1 c, or 42.0 percent. At the dear end — around 215.9 c/L — tax would be 72.2 c, but only 33.5 percent, because the retailer and the barrel have taken a bigger slice of a bigger number. Those cheap and dear points are the usual range of the cycle, not the single cheapest or dearest day ever.
Verdict. The 40 percent line is not made up, but it describes the world after 1 August, and even then only near the bottom of the cycle. Today, with relief in force, you are closer to 30 percent. Once the full excise returns, most days land at a third-and-a-bit up to a touch under 40 — a range of about 33.5 to 42 percent. Today’s relief-era range is lower again, roughly 26 to 32 percent. Both ranges are read the same way: the cheap and dear ends are the 5th and 95th percentiles of the daily-median series, so they mark where the cycle usually sits, not the record days.
So what, for you. Two plain things follow. First, the tax on a litre barely changes from week to week — the excise is fixed and the GST moves by cents. So when the pump price jumps 30 c overnight, that is not the government; that is the cycle. The one dated exception is 1 August, when the excise floor lifts 16 c in a single step — about 17.6 c/L at the bowser once GST stacks on top, or roughly $8.80 on a 50 L fill. Second, the cheaper you buy, the higher the share that went to tax — a strange kind of comfort, since at the trough more of your dollar was the unavoidable part and less was margin. The lever you can actually pull is timing and where you fill, not the tax. Watch the price where you buy and fill near the bottom — today’s prices are on the Pinly Fuel map.
Diesel drivers get asked this too, and the answer surprises people. Diesel carries the identical excise and the same one-eleventh GST as petrol — not a cent more, at 36.6 c today or 52.6 c from August. Today’s Brisbane metro diesel median is 214.9 c/L across 473 stations, so the tax share works out to 26.1 percent right now, and 33.6 percent once the full excise returns. Lower than petrol either way, but only because the pump price is higher, so the flat excise is a smaller slice of it. Same tax, bigger bill — the lower share is arithmetic, not a discount. One label caveat on that diesel median: of those 473 stations, 360 report a “premium diesel” price and 179 the plain-diesel code, with 66 carrying both, so 214.9 pools the two labels the way the app does — split out, plain diesel reads 213.9 and premium 216.9, and the pooled median here lands between them. It moves the diesel share by a fraction of a point, not the story.
One honest limit. Only the pump price is ours, read to the report-time level from the QLD feed. The excise and the one-eleventh GST are ATO rules, not our data. The excise sits at 36.6 c under the relief measure until 1 August, then returns to the full indexed 52.6 c — that step-up moves the ULP share from about 30 percent to about 39, so we have shown both rather than pick one. The cheap and dear figures here are the 5th and 95th percentiles of the daily-median series over our base window, so they describe where the cycle usually sits, not the single cheapest or dearest day ever recorded. Your own suburb on your own day will differ by a few cents. But the shape holds: tax is a bigger share when fuel is cheapest, and about 30 percent of what you pay today.