The Association of British Insurers (ABI) has warned that if UK motorists plan to drive abroad after 29th March, they need to have a Green Card to prove they have insurance.
Both British businesses and individuals driving in Europe or across the Northern Ireland/Republic of Ireland border would be affected by this change.
Since the card needs to be ordered a month before travel, the Association said drivers should act soon or risk breaking the law.
Although European insurance authorities agreed to waive the need for Green Cards in the event of a no-deal Brexit in May 2018, it has not been confirmed by the European Commission.
"As it looks increasingly possible that a no-deal Brexit may happen, we want all insurance customers to know the facts about what this means for them,” Huw Evans, director general of the ABI, said.
Drivers may also need to get an International Driving Permit (IDP) to drive abroad, in case of a no-deal Brexit.
Prime Minister Theresa May, who narrowly survived a no-confidence vote the day after her plan for leaving the EU was rejected, is to meet MPs today to try to find a way forward for Brexit.
She must present a new plan for EU withdrawal to Parliament by 21st January.
