The ‘border adjustment mechanism’ aims to create a level playing field while also encouraging decarbonisation

The biggest shake-up of green trade rules for decades comes into force today, as companies selling steel, cement and other high-carbon goods into the EU will have to prove they comply with low-carbon regulations or face fines.

But a lack of clarity on how the rules will be applied, and the failure of the UK government to strike a deal with Brussels over the issue, could lead to confusion in the early stages, experts warned.