Car tax CO2 emissions UK — CO2 is the primary factor determining how much road tax you pay. Here is everything you need to understand about CO2 and how it determines your Vehicle Excise Duty in 2026.
What Is CO2 and Why Does It Determine Road Tax?
Carbon dioxide (CO2) is the greenhouse gas produced when fuel is burned in an engine. The UK government links road tax to CO2 emissions to incentivise low-polluting vehicles and discourage high-emission choices. The more CO2 your vehicle produces per kilometre, the higher your road tax band.
How to Find Your Vehicle's CO2 Figure
- V5C logbook (Section D): Shows the official CO2 figure in g/km
- MOT certificate: Lists CO2 for vehicles tested from 2018 onwards
- Manufacturer's specification: On the Certificate of Conformity or dealer listing
- GOV.UK vehicle enquiry: Enter registration to see CO2
VED Bands by CO2 Emissions (First Year)
- 0g/km: £0 (pure electric)
- 1-50g/km: £10 (PHEVs)
- 76-90g/km: £130
- 131-150g/km: £600
- 191-225g/km: £1,565
- Over 255g/km: £2,605
Why CO2 Can Vary Between Similar Cars
Two vehicles of the same model and engine can have different CO2 figures due to optional equipment, tyre type, aerodynamic modifications, and test cycle variations. The figure on your specific V5C is the official one that applies — not a general model figure from brochures.
Conclusion
Car tax CO2 emissions UK is the single most important factor in your road tax bill. Find your CO2 in Section D of your V5C. Use our car tax calculator to see your exact VED band.