New carbon emissions (CO2) based vehicle registration tax and motor tax systems were introduced for private cars in 2008. The public consultation process on the proposed changes, in December 2006, made it clear from the outset that the objective of the new motor tax system was to influence the future purchasing decisions of consumers in favour of lower carbon emitting vehicles and that cars registered before the introductory date would continue to be taxed in future years under the existing motor tax system where a graduated tax system applies, depending on the engine size of the vehicle. Any retrospective application of CO2 based charges to pre-2008 vehicles would not have been possible as CO2 values for these vehicles had not been collected as the basis for a fiscal charge and were either not available or, where recorded, had not been authenticated for business purposes.
The last general round of increases in motor tax took effect from 1 January 2013. While some increases for the higher emitting CO2 bands were announced in Budget 2020, taking effect from 1 January 2021, there were no rate increases for pre-2008 vehicles. Changes to the rates and to the structure of the motor tax system are generally made at Budget time and are a matter for consideration in that context. The Minister for Finance has ultimate responsibility for the setting of the rates of motor tax and vehicle registration tax.