Investigations by Revenue officials found marked mineral oil (green diesel) in the fuel tank of 2,593 cars over the last six years according to latest figures.

It is an offence to use green diesel in a motor vehicle or to keep it in the fuel tank of a vehicle. 

If Revenue detects green diesel in a vehicle, they can, if it is a first offence, "offer the person concerned an opportunity to resolve the matter by way of payment of a compromise sum".

In response to a parliamentary question raised by the Social Democrats TD, Aidan Farrelly, the Tánaiste and Minister for Finance, Simon Harris, said that 1,601 "compromise sums" have been paid since 2020.

According to the Tánaiste, this resulted in more than €1.9 million being paid out by drivers in "compromise sums".

Green diesel

The Minister for Finance has also highlighted that anyone with green diesel in a fuel tank can be liable to a fine of €5,000.

"In cases where marked mineral oil is found in the fuel tank of a commercial vehicle, the normal course would be to proceed by way of the institution of a prosecution under section 102 of the Finance Act 1999.

"In certain cases, the vehicle in which the marked mineral oil is detected is seized by Revenue," the minister added.

Latest figures that from 2020 show that 493 fines have been issued by courts in relation to green diesel offences.

The total value of these fines amounted to more than €1.3 million.

Revenue

Earlier this month, Revenue confirmed that 23 people were on its latest list of tax defaulters for "misuse of marked mineral oil" (green diesel).

The list specifically covered the period October 1, 2025 to December 31, 2025.

According to Revenue, these 23 people were handed court fines totaling €56,450.

It also confirmed that a one-month custodial sentence was also imposed "suspended for 12 months on own bond of €100".