What the NOx charge will cost you.
Since 2020, a Nitrogen Oxide (NOx) levy has formed part of the VRT on nearly every car registered in Ireland. Here is the full scale of charges, where to find your car’s NOx figure, and what it costs when that figure is missing.
Work out your chargeWhat the NOx charge is.
Nitrogen Oxide (NOx) emissions have been taxable since 1 January 2020. The charge applies to all Category A vehicles (passenger cars), excluding electric vehicles but including hybrids.
The NOx charge is a component of Vehicle Registration Tax. It’s added to the carbon dioxide charge to give the total tax due:
CO2 charge + NOx charge = Total VRT payable
NOx is charged on milligrammes per kilometre (mg/km) as recorded on the Certificate of Conformity. For heavy-duty vehicles it is milligrams per kilowatt hour (mg/kWh). Where a document shows the figure in grammes per kilometre, Revenue converts it to milligrammes at registration, so it won’t change the tax due.

Where to find your NOx figure.
To finalise registration you must provide evidence of the vehicle’s NOx emissions. Where you look depends on whether the car is new or used.
New vehicles
For a new vehicle, the NOx emissions figure is recorded on the vehicle’s Certificate of Conformity (CoC). Obtain this from the seller or the manufacturer.
The CoC must be uploaded before the vehicle’s registration inspection.
Used vehicles
The Foreign Registration Certificate (FRC), mandatory for all used imports, may show a NOx figure. On UK imports, it’s usually in box V.3 of the V5C. Japanese imports can be sourced from Japan’s Ministry of Land, Infrastructure, Transport and Tourism.
If it isn’t on the FRC, obtain the CoC from a main dealer or the manufacturer. If no figure can be provided, the flat charge applies.
Work out the charge on your car.
Revenue applies one sliding scale to every vehicle. Enter the car’s NOx figure to see the charge for diesel, petrol or hybrid.
The scale is the same for every vehicle: €5 per mg up to 40 mg/km, €15 per mg from 41 to 80, €25 per mg above 80.
No NOx figure on record? You pay the maximum.
Revenue applies a flat charge where satisfactory evidence of a vehicle’s NOx emissions cannot be produced at registration, no matter how clean the engine actually is.
The NOx charge is one component of VRT. It is added to the CO2 charge to give the total payable. Figures are based on Revenue’s published NOx scale and are for guidance only. Source: Revenue.ie
The NOx figure lives in box V.3.
On a UK V5C registration certificate, exhaust emissions are grouped under section V. The NOx reading is in box V.3, shown in g/km or g/kWh. Here’s the full list of categories you’ll find on the document.
Revenue’s four sample vehicles.
These are Revenue’s own published calculations. Open the two flagged cars to see what happens when a NOx figure cannot be produced.
2016 4-door saloon1.8 l petrol · 8 mg/km NOx €40NOx charge
2006 5-door SUV3 l diesel · 90 mg/km NOx €1,050NOx charge
2015 5-door hatchback1.9 l diesel · no NOx figure producedNo NOx figure €4,850NOx charge
2010 2-door sports coupe5 l petrol · no figures producedNo CO2 or NOx figure €600NOx charge
Figures as published by Revenue. Where an older document shows a CO2 figure on the NEDC test, Revenue converts it to a WLTP equivalent before applying the rate. The CO2 values above are the converted figures.
Get the full VRT figure, NOx included.
The Cartell VRT Calculator combines the CO2 and NOx components into one figure, so you know the true cost before you buy or import.
Calculate my VRT