The September fuel hit is no longer a forecast.
From Wednesday, 2 September, South Africans will pay more at the pump. Petrol rises by roughly 96 cents to R1.07 a litre. Diesel climbs by about R2.71 to R2.92. Illuminating paraffin increases by around R2.12 a litre.
The figures in the supplied adjustment are ranges rather than a single national pump price, so the final amount motorists see depends on the fuel grade and location. Inland prices also differ from coastal prices.
That distinction matters.
The first hit is obvious. You fill the tank and pay more.
The second one takes longer to arrive.
Diesel is deeply tied to the movement of goods. Trucks, commercial vehicles and other operators that depend on diesel now have a larger fuel bill to carry. That cost has to go somewhere: into margins, transport charges or, eventually, the prices charged for goods.
This is why September's diesel increase matters beyond the forecourt.
The Central Energy Fund's under-recovery figures had already pointed towards an increase before the official adjustment was published. The local fuel-price formula responds to international petroleum prices and movements in the rand, alongside domestic taxes and levies.
The result is a monthly mechanism that can move sharply when the underlying inputs move sharply.
And 2026 has already been volatile.
Fuel prices have moved by several rand in both directions since March. That means households and businesses are not starting September with a blank page. Earlier increases and decreases have already changed transport and operating costs.
There is also a continuing question around the residual impact of the slate levy. The supplied information does not provide enough detail to state precisely how much of September's final adjustment is attributable to that component, so it should not be presented as a settled number.
The same applies to international oil risk.
A renewed oil-price spike could put pressure on a future monthly adjustment. It does not, by itself, change the price taking effect this Wednesday.
For motorists, the calculation is simple: every litre costs more.
For taxi operators and other transport businesses, the calculation is harder. Fuel is an operating expense, and a large diesel increase can put pressure on already tight margins.
For informal traders, delivery businesses and small operators, there is another layer. The vehicle is often part of the business itself. Higher fuel costs can reduce what is left after a day's work.
Then there is food.
Food does not become more expensive simply because diesel rises. But fuel is one input in the supply chain that moves food from farms, factories and warehouses to shops, markets and consumers. How much of this month's increase gets passed through will depend on individual businesses and the wider cost environment.
That is the part worth watching.
South Africa adjusts regulated fuel prices every month using a formula linked to international petroleum prices, the rand-dollar exchange rate and domestic components including taxes and levies.
The September adjustment is therefore not simply a retailer deciding to charge more.
The Central Energy Fund's under-recovery data showed the direction of travel before the Department of Mineral and Petroleum Resources published the official adjustment.
What is confirmed is the increase taking effect Wednesday.
What remains open is the size of the downstream effect: how much transport operators absorb, how much businesses pass on and how much eventually reaches consumers.
The slate-levy contribution also requires precise final figures before it can be described more definitively.
If you drive every day, the increase lands immediately in your fuel budget.
If you rely on taxis, the effect may appear later through operators' costs rather than directly at the pump.
If you run a business that delivers goods or uses commercial vehicles, diesel becomes a bigger line item from Wednesday.
If you buy food, household goods or anything transported by road, the diesel increase matters because transport sits inside the supply chain.
The effect will not be identical for every household. Someone filling a small petrol tank once a month will experience the increase differently from a long-distance driver, taxi operator or business running a fleet.
But the direction is the same: September starts with another increase in the cost of moving people and goods.
* How much of the diesel increase will reach food and transport prices by October?
* How much will businesses absorb rather than pass on?
* Will Treasury consider further fuel-levy relief if another period of high international oil prices develops?
* And how much more pressure can households absorb if fuel rises again after the September adjustment?
For Wednesday, there is no mystery about the direction.
The price goes up.
The bigger story is what follows the pump.