Post-Brexit checks on some EU goods coming into Great Britain have been delayed by six months in order to give businesses more time to prepare.
The government said the new timetable would help firms recovering in the wake of the Covid-19 pandemic.
The need for health certificates on imports such as meat and milk will be pushed back from next month to October.
And in-person inspections on such animal products due from July will now begin in January 2022.
It is the second time that the timetable for these checks, originally due after the post-Brexit transition ended in January 2021, has been put back.
The European Union has been implementing full checks on goods sent from the UK since the start of this year.
Cabinet Office Minister Michael Gove said the disruption caused by the pandemic had "lasted longer and has been deeper than we anticipated".
'Chopping and changing'
In a statement outlining the changes, he insisted the government had been "confident of being ready on time" for the checks to take effect.
But he added: "We have listened to businesses who have made a strong case that they need more time to prepare."
Under the revised timetable:
Importers of animal products will have to pre-notify officials from 1 October, instead of next month
Safety and security declarations on imports will be pushed back from July to January 2022
Customs declarations will be required at the point of import on all goods from the same time
Checks on live animals and low-risk plant products will take place from March 2022
The British Retail Consortium, which represents everything from major supermarkets to fast food chains and online businesses, said it would have been "foolhardy" not to delay checks given the current state of border infrastructure and IT systems.
Its director of food Andrew Opie said the new timetable had come "in the nick of time," with many border posts "little more than a hole in the ground".
He added that pushing ahead without a delay "might otherwise have seen empty shelves for some products".
He urged the government not to "rest on its laurels," and use the next six month to "establish and communicate the new systems" with businesses.
Labour's shadow Cabinet Office minister Jack Dromey said the government's "chopping and changing" of rules "smacks of ill-preparedness and incompetence".
"They have had years to prepare for this but can't stop missing their own deadlines," he added.
"The government need to pull their sleeves up, listen to businesses who have been desperately coming forward with practical solutions, and get this sorted."
This extension is not ideal, but it does mean that supermarket shelves, for example, should be kept relatively well-stocked during the recovery from the pandemic.
It is far from clear that all port infrastructure would have been ready to cope with these import arrangements.
It is theoretically possible that other countries exporting to the UK would argue these grace periods violate key world trade principles on offering the same access to all countries.
In practice, in the middle of a pandemic, it seems unlikely that a few months' continuation of favourable import arrangements for EU firms would really lead to a significant backlash.
British exporters that are facing non-tariff barriers in trade with the EU and even with Northern Ireland, might, however, express concern about the impact of EU competitors having ongoing free access to the UK market.
Effectively there has been a post-Brexit transition period - but only for EU firms exporting into the UK.
