Ifo Institute: Diesel Fuel Discount Only Partially Passed On to Consumers

The picture is different for diesel. The Ifo Institute determined an average pass-through of just 12 cents per liter for diesel. "Beim Diesel wurde allerdings nur eine Weitergabe von durchschnittlich 12 Cent pro Liter errechnet", according to the institute. As a result, part of the tax cut did not reach consumers but apparently ended up with the oil companies, as ifo doctoral researcher Christian Gréus emphasizes: "Die unvollständige Weitergabe beim Diesel bedeutet, dass ein Teil davon bei den Mineralölkonzernen gelandet ist".

Methodology and Comparison with the Monopolkommission

The ifo researchers based their estimate on a comparison with fuel prices in France. This allowed normal price movements to be separated from the effect of the fuel discount. According to the institute, the calculations are based on prices up to June 25, 2026.

The Monopolkommission (Monopoly Commission) had also found approximately two weeks ago in a study that the fuel discount was not passed on in full. Based on prices up to June 11, it calculated a somewhat higher pass-through for diesel and a somewhat lower pass-through for gasoline than the Ifo Institute. "die Preise bei Diesel nur um durchschnittlich 12 Cent pro Liter gesunken", according to its analysis. The mineral oil and energy industry association en2x, by contrast, had consistently stated beforehand that the tax reduction had been passed on to customers in full.

Outlook: Rising Prices Expected in July

With the expiration of the fuel discount at the end of the month, the Ifo Institute now expects rising fuel prices. The Ifo Institute anticipates rising prices once the fuel discount expires at the end of the month. However, the actual magnitude will depend primarily on the development of the oil price, as Ifo expert Ramona Schmid explained: "Wie hoch es geht, wird vor allem von der Entwicklung des Ölpreises abhängen. Da dieser zuletzt gesunken ist, haben auch die Kraftstoffpreise nachgegeben".

Should the USA and Iran actually reach an agreement, fuel prices would normalize again, according to the institute. At the same time, the researchers view the expiration of the measure positively overall: the cost of the fuel discount amounted to 1.6 billion euros, which is why letting it expire is the right decision from the institute's perspective.

Politically, the end of the relief has already been decided. The Union and SPD had spoken out against extending the fuel discount and pledged to respond quickly to any significant price increase. The coming weeks at the fuel pumps will show how strongly the removal of the tax relief actually impacts prices – and to what extent the international oil market influences developments.

This news was broadcast on June 29, 2026, on the Deutschlandfunk program.