A major new rules change will soon push certain motorists “into higher tax bands”, according to experts. 

A stricter emissions test for plug-in hybrid electric vehicles is expected to be used for benefit-in-kind car tax calculations next year. 

Under current rules, vehicles follow the Euro 6d emissions standard to calculate their pollution and determine how much they will need to pay.

However, officials could soon launch a consultation looking at whether a Euro 6e-bis emission standard should come into effect in Great Britain in 2026.

The new test comes with new standards and is likely to dramatically increase the CO2 rating of certain company cars.

It means vehicles likely to hover between two different tax bands may find the new sensitive test tips them over the edge.

Speaking to Fleet News, Alan Bastey, customer services director at Zenith, said many plug-in cars would likely be bumped into higher bands and therefore pay more.

He said: “There will be a small number of PHEVs that will survive under 50 grammes, but not very many, and not the popular ones either.

“That utility factor does mean most will bump up into the higher tax bands. 

“In January 2027, the utility factor changes again… What survives this time around is going to be hit again with a new utility factor which makes the CO₂ even higher.”

DfT predictions show that a PHEV with a current CO2 figure of 10g/km and electric range of 50 miles could increase to 30g/km. 

Models with a current CO2 figure of 30g/km and electric range of 50 miles could face even bigger consequences. 

These models could see their Co2 readings rise to 90g/km which would have a sizeable impact on benefit-in-kind rates.

These cars are currently charged a BiK rate of 9% but similar models would pay 24% if the new updates come into effect.

The Treasury has already confirmed that the rules would apply to brand vehicles registered after January 1, 2026.

However, in a boost for used car owners, officials said second-hand cars will not be subjected to further emissions testing and will remain at their current rates.