The 'implementation period' set out in the withdrawal agreement governing the UK's departure from the EU ends on 31 December 2020. At this point, all existing trade arrangements between the UK and the EU will come to an end, while trade agreements between the EU and third countries will no longer apply to the UK.
If the UK and EU are unable to negotiate a new trading agreement before the implementation period ends, their trading relationship will revert to World Trade Organisation (WTO) terms at that point.
Brexit advisory expert Clare Francis of Pinsent Masons, the law firm behind Out-Law, said: "With less than four months to go until the end of the transition period, the news of critical gaps in the border plans is unwelcome news for businesses, many of which are still rebuilding supply chains after the significant impact of Covid-19".
"Further disruption for critical supplies will be damaging for business, and even more so if it persists for a longer period due to systems not being ready or not being adequately tested. For manufacturers operating on a 'just-in-time' supply chain this is even more critical. Whilst all businesses can take steps to prepare now, the lack of certainty leaves precious little time for companies to adapt complex supply chains and processes," she said.