There is no single motor-tax calculation that works for every Irish car. The key starting point is the vehicle’s first registration date, not the year it changed owner in Ireland. Using the wrong CO2 test value or assuming every car is taxed by engine size can produce a misleading estimate.
| First registration of the vehicle | Main basis for private-car tax |
|---|---|
| Before 1 July 2008 | Engine capacity (cc) |
| 1 July 2008 to 31 December 2020 | CO2 emissions measured under NEDC |
| From 1 January 2021 | CO2 emissions measured under WLTP |
Cars first registered between 1 January and 30 June 2008 have a transitional history: the official motor-tax guidance says they initially used engine capacity and moved to the CO2 system at a later renewal where that was financially beneficial. For an imported car, use its country-of-origin first-registration date and verify how Revenue or the motor-tax system has classified it.
The practical check is to find the vehicle’s registration certificate and the relevant emissions or engine details, then use the current rate table on Motor Tax Online. Do not copy a rate from an old forum post: bands and amounts can change, while the underlying basis also depends on the vehicle’s registration history. For a used-car comparison, compare annual tax alongside fuel, insurance and expected maintenance rather than treating a low tax band as proof that the car is cheaper to own.
This page is about how to identify the applicable rate, not a replacement for the official calculation. Confirm the amount using the vehicle registration number and the current Department of Transport service before buying or renewing.
