For some UK firms, January 1 may be when Brexit gets real.
The dawn of the new year will see the introduction of much-delayed border control checks.
That will affect businesses importing $314 billion of goods a year from the EU.
From Saturday (January 1) they will have to supply full customs declarations.
Traders will also have to prove that goods are allowed in tariff-free.
The UK's Federation of Small Businesses says that's likely to cause significant disruption.
And that at a time when trade is already being hit hard by health worries and labor shortages.
The FSB says its polling shows many small firms aren't aware of the change, with only one in four of those who are being prepared for it.
An earlier survey by the British Chambers of Commerce showed 45% of companies finding it very or relatively difficult to trade goods with the EU.
That's up from 30% when the Brexit deal kicked in.
Supporters of Brexit say it will, in the long run, allow the UK to trade more freely around the world.
Bigger firms have taken on staff to deal with extra paperwork.
But many little companies are struggling, finding that the extra costs make smaller consignments of goods unviable.
A body representing the frozen and chilled foods trade said costs per shipment were up more than $500.
Additional veterinary checks will come in for some food imports from July.