The NOx levy is a new tax introduced on all vehicles (excluding electrics but including hybrids) registered after 31 December 2019, that are liable for a Nitrogen Oxide (NOx) emissions charge as part of the VRT payable on a car. The charge applies to new car purchases and used imports. This charge replaced the 1 per cent diesel surcharge.

There are two components to Vehicle Registration Tax (VRT), the NOx charge and the CO2 component. 

The NOx figure is located on the vehicle logbook (V5) if it is not available on this document then the existing Certificate of Conformity (CoC) should contain a NOx figure. If in doubt a manufacturer may be able to clarify which figure to use. 

Charges are applied on a per-milligramme basis, based on a car’s officially recorded emissions of NOx per kilometre. The scale below outlines the amount payable. 

Charges are applied on a per-milligramme basis, based on a car’s officially recorded emissions of NOx per kilometre. The scale below outlines the amount payable. 

The NOx charge will be capped at a maximum of €4,850 for diesel vehicles and €600 for other vehicles.

In order to register a vehicle, a person must first book an appointment at an NCTS centre to have the vehicle examined to ascertain whether or not it meets the definition of mechanically propelled vehicle for VRT purposes. Visit the NCT website  where the have further information on the VRT process in their FAQ section. 

Carbon Dioxide charge + NOx Charge = Total VRT payable.

The Revenue Commissioners website provides a calculator that will help determine an estimate of the charge payable, the potential NOx levy for the vehicle. Their spreadsheet may assist to identify the vehicle with its estimated NOx emissions value.

The website also provides information on NOx and examples of  VRT calculations.   

The nitrogen oxide (NOx) emissions-based charge is welcomed taxation as it could reduce the number of older used imports coming into Ireland. Since 2016 there has been over 150,000 imported cars that do not meet the latest EU emission standards, which in effect means Ireland has become the dumping ground for older cars the UK doesn’t want. This is bad news for Ireland’s environment. The introduction of the NOx charge will impact on older higher emitting used imports which, unlike the previous diesel surcharge, will penalise older cars with higher levels of pollutants.

Although there were previous emission regulations, the starting point for the Euro emissions standard referred to as ‘Euro standards’ was 1991 with ‘Euro 0’ ‘Euro 0' (Arabic numerals) for passenger cars and in 1992 with ‘Euro I' (Roman numerals) for commercial vehicles.

In 1992 Euro 1 saw the introduction of catalytic converters become compulsory on new cars. There have been a series of Euro emissions standards since then, with Euro 6 the current standard. Euro 6 was introduced on 1st September 2014 and was rolled out on vehicles registered in September 2015. 

The aim of Euro emissions standards is to reduce the levels of harmful exhaust emissions chiefly:

• Nitrogen oxides (NOx)
• Carbon monoxide (CO) 
• Hydrocarbons (HC)
• Particulate matter (PM)

Over time innovation and technologies have contributed to improvements in engine management systems and exhaust after-treatment systems, which have helped meet progressively tighter emission standards. Under the Euro 6/VI standards all new diesel cars and all new trucks are now fitted with particulate filters. Many commercial vehicles also use Selective Catalytic Reduction (SCR) in combination with a urea-based additive (trademark AdBlue®) to help reduce NOx emissions.

You can normally work out what your car's Euro standard is from its age but there are other factors which can contribute too. Check with the manufacturer to be certain. The table below acts as a guide to show how the different Euro emissions categories are applied to new vehicle models approved after a specific date. 

• Every new car placed on the market must undergo a test, WLTP is a new type of test. Under EU law, the Worldwide Harmonised Light Vehicle Test Procedure (WLTP) laboratory test is used to measure fuel consumption and CO2 emissions from passenger cars, as well as their pollutant emissions. The new test is designed to be far more stringent, requiring vehicle engines to replicate far more demanding and strenuous driving; as a result, the CO2 values delivered under the test have always been expected to be higher.
• From September 2017, the old NEDC (New European Driving Cycle) lab test for cars was replaced by the new WLTP test. The same car can go through both tests and will have higher emissions recorded on the new test. September 1st 2018 Vehicle Manufacturers had to ensure that all new Cars and Light Commercial Vehicles placed on the market have been tested under the new WLTP test. From the start of 2019 WLTP fuel consumption and CO2 emission values have been used for consumer information purposes.

Image source ACEA 

The old NEDC test was based on a theoretical driving profile, while WLTP uses real-driving data.

Image source ACEA 

WLTP will be the basis for taxation for cars from January 2021. The new test is designed to be far more stringent, requiring vehicle engines during its lab test to replicate far more demanding and strenuous driving. As a result, the CO2 values delivered under the test have always been expected to be higher. 
 WLTP Test (more rigorous test) will produce higher CO2 value than older NEDC Test. 
 Ireland’s Registration Tax (VRT) & Road Tax will move from the older NEDC emissions test to WLTP Jan 2021. 
 It was never intended that consumers should have to pay increased taxes as a result of this changeover and indeed the EU Commission has already commented on this, while noting that Taxation is a matter for each Member State: "It should be noted that the introduction of WLTP does not necessarily result in higher car taxes... if the adjustment of national car taxation schemes takes account of the expected increase in CO2 emissions under WLTP." 

Image source ACEA 

·   The WLTP test will facilitate more realistic driving conditions which will include, 

• More realistic driving behaviour;
• A greater range of driving situations (urban, suburban, main road, motorway);
• Longer test distances;
• More realistic ambient temperatures, closer to the European average;
• Higher average and maximum speeds;
• Higher average and maximum drive power;
• More dynamic and representative accelerations and decelerations;
• Shorter stops;
• Optional equipment: CO2 values and fuel consumption are provided for individual vehicles as built;
• Stricter car set-up and measurement conditions;
• Enables best and worst-case values on consumer information, reflecting the options available for similar car models.