There will be a "grace period" for any changes made to customs checks and controls in a crash-out Brexit, Taoiseach Leo Varadkar has said.
The Government is under pressure to outline plans for a no-deal Brexit, and last night Mr Varadkar said there will have to be checks near the border with Northern Ireland.
Fianna Fail leader Micheal Martin warned that the Government must be "absolutely honest" and "up front" about plans for customs checks.
During a visit to Co Waterford, Mr Varadkar was asked how farmers will manage the cross-border milk trade.
"That is one of the things that is yet to be sorted out in detail," he said.
"I appreciate that that is an issue of real concern for people, particularly those who operate agri-food on and along the border and that has yet to be worked out".
He said he appreciated that it is causing "worry and confusion".
"As soon as we have clarified those arrangements with the European Commission, we will inform the public and business," he said.
"What I can say is there won't be any sudden decisions that people are expected to implement within a few days.
"There will be a lead-in time and a grace period and a phase-in time for any changes."
Meanwhile, Ireland is set to be handed one of the top jobs in the European Commission and major influence on future trade talks with the UK.
Phil Hogan is in line to be appointed to the position of Trade Commissioner, a job that will put him at the centre of negotiations on the future relationship between the EU and UK.
The appointment will be seen as evidence that the EU is standing firmly by Ireland.
Mr Hogan has been one of the most vocal critics of the UK's tactics in the current Brexit negotiations.
EU member states are this weekend lobbying incoming commission president Ursula von der Leyen for jobs, but sources said Mr Hogan is the clear front-runner for trade.
It comes after the UK finally tabled an alternative proposal to the backstop that would involve an all-Ireland food standard zone. However, the idea was quickly rebuffed as unsatisfactory by the EU.
The Government made no secret of the fact it was lobbying for a significant job for Mr Hogan in the wake of Brexit.
Commissioners are expected to put the wider EU project to the forefront of their work, rather than domestic interests.
However, in recent years it has also been accepted that they can reflect the view of their home country.
The Trade Commissioner is responsible for representing the EU at the World Trade Organisation and other international forums.
While they will not directly head up trade negotiations with the UK, sources said the person would be a "central player" in the process.