Your VRT NOx calculator — the levy in euros, in under a minute
Choose your import's origin — UK, Northern Ireland or Japan — enter the reg or the make and model in the tool on the right, and get your NOx charge plus total VRT estimate using Revenue's 2026 rates. No signup, no email, no waiting for an NCTS appointment to find out the number that matters.
- Plates calculated
- 68K+
- NOx charge estimated
- €47M+
- Match rate
- 98.4%
Plates calculated
VRT estimated
Match rate
The NOx charge in five facts
Before the full breakdown below, here is everything you need to sanity-check a number the calculator gives you.
Three cumulative bands: €5 per mg/km (0–40 mg/km), €15 per mg/km (41–80 mg/km), €25 per mg/km (81 mg/km and above).
Capped at €4,850 for diesel vehicles and €600 for petrol and other fuels.
Your total VRT = CO2 charge + NOx charge; the NOx part runs on mg/km, not on the OMSP.
Battery electric vehicles (BEVs) are exempt from the NOx charge and pay €0 on this component.
The NOx value is read in mg/km — entering g/km by mistake understates the charge by a factor of 1,000.
Four steps from origin to NOx charge
No paperwork, no account. Pick where the car is coming from, add a few vehicle details, and the calculator on the right returns every component of your NOx charge and total VRT.
Pick the origin
Select UK, Northern Ireland or Japan in the calculator above. The paperwork behind the NOx figure differs by market, so this sets the right fields for your import.
Enter the reg or the model
Type the registration for a UK or NI car, or the make, model and variant for a Japanese import, and the tool pulls the specification for you.
Read OMSP, CO2 band and NOx
The calculator returns the OMSP Revenue would apply, the CO2 band percentage, and the NOx charge worked out from the certified mg/km figure — the three pieces of your VRT bill.
Download the PDF
Save the estimate as a PDF report so you have every figure to hand at your NCTS appointment, ready to compare against the amount Revenue confirms on the day.
NOx charge bands and caps for 2026
The 2026 NOx charge uses three cumulative bands: €5 per mg/km for the first 0–40 mg/km, €15 per mg/km for 41–80 mg/km, and €25 per mg/km for anything above 80 mg/km. The rates and caps have stayed unchanged since 2020, and Budget 2026 made no adjustment to the levy.
The three NOx bands explained
The charge is cumulative, not a single rate applied to the whole figure: you pay the low rate on the first slice of emissions, a middle rate on the next slice, and the top rate only on what's left above 80 mg/km.
| NOx emissions (mg/km) | Rate | How it applies |
|---|---|---|
| 0–40 mg/km | €5 per mg/km | Charged on the first 40 mg/km |
| 41–80 mg/km | €15 per mg/km | Charged on the next 40 mg/km |
| 81 mg/km and above | €25 per mg/km | Charged on everything above 80 mg/km |
So a car emitting 60 mg/km pays €5 on its first 40 mg (€200) and €15 on the remaining 20 mg (€300), for a NOx charge of €500 — not €900 as a flat €15 rate would suggest. This stepped structure is why two diesels with similar-looking emissions can end up with very different bills.
Diesel and petrol caps
However high the emissions climb, the NOx charge is capped by fuel type, which protects owners of older high-NOx diesels from an unlimited bill.
- Diesel vehicles: capped at €4,850.
- Petrol and all other fuels: capped at €600.
Why this matters: if Revenue cannot establish a vehicle's NOx value from any source, it applies the maximum default charge — €4,850 for diesel and €600 for other fuels — so it always pays to have a documented mg/km figure ready before you register.
How NOx and CO2 combine to make your total VRT
Your total VRT is the CO2 charge plus the NOx charge: the CO2 component is a percentage of the car's Open Market Selling Price (OMSP), while the NOx charge is added separately on top of it. Neither one travels alone — here is how the two fit together.
The CO2 component
A percentage of the vehicle's OMSP, set by which WLTP band the car's CO2 emissions fall into. Rates start at 7% of the OMSP for the cleanest cars at 0 g/km and rise through 20 bands as emissions increase. Because it's tied to market value, the CO2 charge grows with a more expensive vehicle.
The NOx component
Worked out purely from the certified emissions in mg/km and then added on top of the CO2 charge. It takes no account of the OMSP, the CO2 band, or the age of the car beyond the registration cut-off — a standalone euro figure from the three bands above.
Where to find your NOx value (and the g/km vs mg/km trap)
Since the whole calculation hinges on one number, here is exactly where to read it and in which unit.
On the V5C and Certificate of Conformity
mg/km, g/km and g/kWh
The unit is where most self-calculations go wrong. Passenger-car NOx is expressed in mg/km, but some documents show it in g/km, and the two are a thousand times apart.
| As printed | Convert | Result |
|---|---|---|
| 0.055 g/km | × 1,000 | 55 mg/km |
| 0.080 g/km | × 1,000 | 80 mg/km |
Heavy-duty vehicles are a separate case: their NOx is measured in mg/kWh, not mg/km, so never plug a heavy-duty figure into a passenger-car calculation.
NOx charge on a 2019 Mazda CX-5 diesel
Rates and units are easier to grasp with a concrete diesel, so here is the full calculation on a real high-NOx model — the kind of SUV that shows up constantly in UK used-car ads.
2019 Mazda CX-5 2.2 SKYACTIV-D AWD
A certified NOx figure of 100 mg/km incurs a NOx charge of €1,300, comfortably under the diesel cap.
Vehicle inputs
| Make / model | Mazda CX-5 2.2 SKYACTIV-D AWD |
| First registration | 2019, UK |
| Fuel type | Diesel |
| NOx | 100 mg/km |
Step-by-step calculation
| Band 1 (0–40 mg/km) | 40 × €5 = €200 |
| Band 2 (41–80 mg/km) | 40 × €15 = €600 |
| Band 3 (81–100 mg/km) | 20 × €25 = €500 |
| Total NOx charge | €1,300 |
Reading the result. Because €1,300 is well below the €4,850 diesel cap, the full amount stands. Only if the emissions were high enough to push the running total past €4,850 would the cap kick in and freeze the charge there.
Adding it to your total VRT. That €1,300 is not the whole story: it is added to the CX-5's CO2 charge (a percentage of its OMSP) to reach the total VRT. So if the CO2 charge came to, say, €3,500, the NOx levy would lift the registration bill to roughly €4,800 before any customs or VAT on the import itself. Swap in your own car's mg/km figure in the calculator above to see where your diesel lands — the gap between a 60 mg/km and a 130 mg/km engine can be well over €1,000.
Which vehicles are affected, and which are exempt
The NOx charge applies to all Category A petrol and diesel cars — including hybrids — first registered on or after 1 January 2020, while fully electric vehicles (BEVs) are completely exempt and pay €0.
Cars in scope
The levy covers Category A vehicles — ordinary passenger cars and SUVs — running on petrol or diesel, and this expressly includes hybrids, which still burn fuel and emit NOx. The trigger is the registration date: any such car first registered on or after 1 January 2020 is in scope, which captures essentially every recent UK, NI or Japanese import.
Exempt and special cases
Battery electric vehicles (BEVs) produce no tailpipe NOx and are therefore exempt, paying €0 on this component. Heavy-duty vehicles are handled differently again — their emissions are measured in mg/kWh rather than mg/km — so the passenger-car bands above do not apply to them.
VRT NOx calculator FAQ
The most common questions about the NOx charge, once the bands and the worked example above are clear.
When and where do I pay the NOx charge?
You pay it together with your VRT at an NCTS centre when you register the car, and registration must happen within 30 days of the vehicle arriving in Ireland. There is no separate NOx invoice — it is bundled into the single VRT payment.
Do plug-in hybrids pay the NOx charge?
Yes. Plug-in hybrids are Category A petrol or diesel vehicles for VRT purposes, so they are charged on the same three NOx bands as any other combustion car — only battery electric vehicles (BEVs) are exempt. Check the PHEV's certified mg/km figure on its Certificate of Conformity before you commit, as it can vary widely between models.
Is the NOx charge the same as the old diesel surcharge?
No. The NOx emission levy replaced the former diesel surcharge on 1 January 2020. Unlike the old surcharge, it applies to petrol and hybrid cars too — every Category A fuel-burning vehicle, not just diesels.
Does importing from Northern Ireland change the NOx charge?
The NOx charge itself is identical regardless of origin. What differs is the surrounding cost: an import from Great Britain can attract customs duty and import VAT at 23%, whereas a qualifying Northern Ireland car may avoid those, but the NOx levy is calculated the same way in every case.
Can I get a NOx refund if I export the car later?
Generally, no — the NOx charge is paid once at registration as part of your VRT bill, and it is not refunded separately if you later export or scrap the car. If you re-export the vehicle, check whether it qualifies under Revenue's general VRT repayment scheme, which treats the VRT as a whole rather than splitting out the NOx component.
What happens if I don't pay the NOx charge on time?
The NOx charge isn't invoiced separately, so missing your registration deadline has the same consequence as late VRT: Revenue can apply interest and penalties on the full amount due, NOx included. Registering the car within 30 days of arrival, and paying at your NCTS appointment, avoids that risk.
Does the NOx charge apply to a campervan or motorhome?
Motorhomes and campervans are usually registered outside the standard Category A passenger-car valuation used for this calculator, so they are assessed individually by Revenue rather than through the standard NOx bands. If you are importing one, contact Revenue or your local Central Vehicle Office for a bespoke valuation before you commit to a purchase.
In summary
Your total VRT is the CO2 component plus the NOx levy. The CO2 side depends on the OMSP and the WLTP band; the NOx side is a standalone figure worked out from the certified mg/km value across the three bands above.
Get both from the calculator above before you commit to a UK, NI or Japanese import. Confirm the mg/km figure — not g/km — on the V5C or Certificate of Conformity, and remember that only BEVs are exempt: hybrids and combustion cars registered from 1 January 2020 are all in scope.
Treat the result as a close estimate, not a binding figure: the definitive VRT and NOx charge is fixed by Revenue at your NCTS inspection.