Without a deal next month, time will be very tight to agree on arrangements before Britain leaves the European Union in March 2019, adding to pressure on businesses to avoid potential losses and move investments.
As negotiators prepare for the final round of talks ahead of a summit in Brussels on December 14th-15th, the Border has emerged as the biggest remaining barrier to Britain's ambition to move to the second phase of negotiations.
Under the Government of Ireland Act 1920, the island of Ireland has been partitioned into two jurisdictions - the Republican of Ireland and Northern Ireland.
The talks were signalled in this week's Budget Red Book, which said: "Early in 2018, the government will publish a call for evidence which will consider the impact of Value-Added Tax and APD on tourism in Northern Ireland, to report at Budget 2018". European Council president Donald Tusk tweeted on Friday (24 November) that "Sufficient progress in Brexit talks at December's European Council is possible".
"May agreed to this time frame", the source said.
"The UK will need to give credible assurances as to how to avoid a hard border before December 4, as it is still unclear how this can be done", the official added.
Fianna Fail initially indicated it might withdraw its threat of a motion of no confidence if Fitzgerald resigned.
She repeated a line she first used in September that Britain would "honour our commitments".More news: Solar system's first Interstellar visitor dazzles scientists
What we want to get down to is the detailed work in relation to the border and to our trading relationships and how it's going to work post-Brexit.
In his speech to the DUP conference this afternoon, Mr Dodds said: "If I'm honest, I did not believe that in 2017 we were heading for a hung Parliament where the DUP would hold the balance of power, but looking back I don't think it was an accident how things turned out. We want to ensure that movement of people and trade across that border can carry on as now".
This decision will be based largely on the success of negotiations so far.
One of the key sticking points is a proposed piece of legislation to protect Irish language speakers in the region.
"The Irish issue is very worrying".
Mrs Foster was speaking on BBC Radio 4 the day after Simon Coveney told an Oireachtas committee that he wanted to see a united Ireland in his political lifetime. If it does not, will the prospect of a snap election distract Dublin to the point where a compromise with Britain ahead of the summit becomes more hard?
Dublin and European Union officials say the best way to avoid a "hard border" is to keep regulations the same north and south.
Britain has rejected the former because it would divide Northern Ireland from the British mainland.