NOx charge calculator
The NOx levy is the part of VRT that depends on paperwork, not on the car. Enter the NOx figure from the V5C (item V.3) or the Certificate of Conformity and the calculator shows the charge step by step. No figure? It shows what the flat maximum costs and what a typical car of that age would pay instead.
The NOx charge is one of two parts of VRT. For the whole figure, valuation and CO2 band included, enter the UK reg on the VRT calculator.
How the NOx charge is calculated
Revenue charges per milligram of NOx per kilometre, in three steps. The steps are cumulative: a car at 60 mg/km pays the first step in full and 20 mg of the second.
| NOx emissions | Per mg/km | Step in full |
|---|---|---|
| First 0 - 40 mg/km | €5 | €200 |
| Next 41 - 80 mg/km | €15 | €600 (€800 cumulative) |
| Everything above 80 mg/km | €25 | until the cap |
Caps: €4,850 for diesel, €600 for petrol, hybrid and plug-in hybrid. A diesel hits its cap at 242 mg/km; a petrol car hits €600 at about 67 mg/km, so on petrol the cap is the realistic ceiling for anything older than Euro 6. The same two figures are charged flat when no NOx evidence is produced at the inspection. Source: Revenue, Calculating the NOx charge, checked 3 September 2026.
Worked examples
| Car | NOx charge |
|---|---|
| 2021 petrol hybrid, 12 mg/km | €60 |
| 2019 petrol, 28 mg/km | €140 |
| 2018 diesel, 46 mg/km | €290 |
| 2016 diesel, 78 mg/km | €770 |
| 2013 diesel, 160 mg/km | €2,800 |
| Diesel, no figure declared | €4,850 |
Typical NOx figures by Euro standard
If you are still choosing a car, the year tells you roughly what to expect. These are the ranges manufacturers typically declare at type approval; the legal limits are 80 mg/km for Euro 6 diesel, 180 for Euro 5 diesel and 60 for petrol from Euro 5 on. Always confirm the exact figure on the V5C before you pay.
| Standard | First registered | Diesel | Petrol |
|---|---|---|---|
| Euro 6d | Jan 2021 onwards | 20-60 mg/km €100-€500 | 10-40 mg/km €50-€200 |
| Euro 6d-TEMP | Sep 2019 - Dec 2020 | 30-70 mg/km €150-€650 | 15-50 mg/km €75-€350 |
| Euro 6b/6c | Sep 2015 - Aug 2019 | 40-80 mg/km €200-€800 | 20-60 mg/km €100-€500 |
| Euro 5 | Jan 2011 - Aug 2015 | 120-180 mg/km €1,800-€3,300 | 30-60 mg/km €150-€500 |
| Euro 4 | Jan 2006 - Dec 2010 | 180-250 mg/km €3,300-€4,850 | 40-80 mg/km €200-€600 |
Where the number lives
- V5C logbook, item V.3. Printed on UK logbooks for most cars registered since 2010. Often blank on older or imported cars, so ask the seller for a photo of that page before you travel.
- Certificate of Conformity (CoC). The manufacturer’s document; NOx is in the exhaust emissions section. Dealers and online services issue copies for roughly €50-€150. Needed when the V5C is blank.
- Not on the DVLA record. The online vehicle enquiry gives CO2 and Euro status but not NOx, which is why our breakdown document shows the Euro standard and the typical range instead.
- Bring it to the NCTS inspection. Revenue does not look it up for you. No evidence on the day means the flat maximum, and getting it refunded later means a formal appeal.
The NOx charge is the cheap part on a modern petrol car and the expensive surprise on an older diesel. The CO2 part is usually bigger still. Check the full VRT for a UK reg, free. How the bands work is on the VRT rates page.