Since 1 January 2020 Nitrogen Oxide (NOx) emissions have become taxable in Ireland. The NOx charge applies to all Category A Vehicles (cars) including hybrid cars not not electric cars.

The NOx charge is a component of vehicle registration tax (VRT).



How to Calculate The NOx Charge

According to the Revenue:

NOx is charged on the basis of milligrams per kilometre as recorded on the Certificate of Conformity. In the case of heavy duty vehicles this will be milligrams per kilowatt hour.

As NOx is a component of VRT, it will be charged according to: Carbon Dioxide charge + NOx Charge = Total VRT payable.


NOx will be charged through the following calculation:


The Revenue also state:

If satisfactory evidence of NOx emissions cannot be provided the following maximum charges will apply:

Diesel vehicles: €4,850


All others: €600



Where can I find a Free NOx Calculator?

There are a number of free NOx calculators that can be found online. As of yet, there are no calculators that successfully calculates the Carbon Dioxide charge and the NOx Charge together to give you the total VRT payable.

You can find a free NOx calculator on the website.

Cartell Nox Calculator

The Cartell Nox Calculator is useful only for calculating Nox. You must work out the carbon dioxide charge separately to find the total cost of VRT for your car.

There is also a free NOx calculator on the Revenue website but it is an excel based spreadsheet that you must download.

NOx calculator

Again, as with Cartell, there is no way as of yet to calculate the full VRT rate. It is likely that Revenue will eventually have a online tool that will calculate the full VRT price including the Carbon Dioxide charge and the NOx Charge together.