Customs checks will be needed somewhere in Ireland if there's a no-deal Brexit.
The government's latest contingency plan concedes checks will be needed on goods and livestock coming from north to south if the UK crashes out without a deal.
But the government insists that doesn't have to happen at the border and it's not planning for a return to customs posts.
Discussions between the government and the European Commission are ongoing about how to protect the single market while also avoiding a border.
Tánaiste Simon Coveney says they have to be realistic about the situation: