New border arrangements for trade between Great Britain and Northern Ireland will come into force on New Year's Day. But Northern Irish trade bodies have warned that businesses don't have enough time to prepare for the change.
Although part of the UK, Northern Ireland will remain subject to some EU rules after the end of the post-Brexit transition period, in order to keep an open land border with the Republic of Ireland, an EU member.
This will effectively create a new regulatory divide in the Irish Sea, with new checks applied to goods sent from the British mainland to Northern Ireland.
Aodhán Connolly, Director of the Northern Ireland Retail Consortium (NIRC), says traders have not been given the technical information to prepare properly, and are still in the dark over new IT systems, labelling requirements and customs checks.
"Quite frankly we have none of the information that we need to be able to trade on 1st January," he told Euronews.
The new measures result from the Northern Ireland Protocol contained in the UK-EU divorce deal.
Connolly said that without a new EU-UK free trade agreement, businesses and households in Northern Ireland will not be able to afford the costs the extra friction would bring.
"That's the difference between a paper customs wall down the Irish Sea, and a brick customs wall down the Irish Sea," he says.
Decisions are needed from the Joint Committee (the EU-UK body charged with overseeing the exit deal), he added, to remove frictions and allow time to adjust to the new arrangements.
On Tuesday the EU and the UK said agreement had been reached in principle on all issues relating to the Northern Ireland Protocol. The NIRC welcomed the news on Twitter but added that more details were needed.
"We're sitting at the moment with over 85 questions that still need answers," he told Euronews earlier, citing a planned waiver system concerning health certificates for products of animal origin. "None of it has been decided, we don't have that technical detail, and quite simply, we haven't known what finally to prepare for."
Watch the interview with Aodhán Connolly on Good Morning Europe in the video player above.