This Tuesday, September 1st, Spanish drivers filling up their tanks will notice a significant change in fuel prices. It won't be the same for everyone: while diesel will receive a larger tax break , gasoline will see a smaller discount. This adjustment is in accordance with the safeguard clause included in Royal Decree-Law 18/2026, which is activated when the year-on-year increase in fuel prices exceeds 15%.
During August, both gasoline and diesel benefited from a 10-cent per liter discount on the Hydrocarbon Tax. Starting in September, diesel will have a 20-cent discount, while gasoline will only have a 5-cent discount. This means that refueling with diesel will be about 12 cents cheaper than on the last day of August , while gasoline will become approximately 6 cents more expensive per liter, assuming all other factors remain the same.
Why does diesel have a bigger discount?
The clause stipulates that if the CPI for each fuel increases by more than 15% year-on-year in July, an extended discount will be maintained. Diesel registered a 15,7% increase , exceeding the limit, while gasoline only rose by 7,3%, thus failing to meet the requirement. Therefore, diesel benefits from a 20-cent discount, while gasoline continues its phased-out schedule.
How much does the price change for the consumer?
According to expert calculations, refueling a diesel vehicle will cost about 12 cents less per liter than on August 31st, while refueling a gasoline vehicle will cost about 6 cents more. This means diesel will be approximately 8 cents cheaper than gasoline , reversing the usual ratio. It's important to remember that the final price also depends on geopolitical factors that affect gasoline prices , the exchange rate, and each station's profit margin, so the price reduction may not be applied exactly.
The price surge and inflation
This change comes after a summer of sharp increases. The average price of gasoline is around €1,72 per liter, and diesel is at €1,86, after eight consecutive weeks of increases. Gasoline has become almost 20% more expensive since the end of June, and diesel nearly 24% . This trend has contributed to the rise in inflation, which reached 4,3% in August, the highest level since 2023.
In short, September 1st brings relief for diesel drivers, who will see a discount of 20 cents per liter, while gasoline drivers will face an increase of about 5 cents in the tax, with practical effects of around 6 cents more per liter. The measure responds to the uncontrolled rise in diesel prices , and prices will continue to depend on the evolution of crude oil prices in the coming weeks.
