Despite concluding EU citizen should not get special treatment after Brexit, a study for the MAC concluded European migrants living in the United Kingdom contribute £2,300 more to the public purse each year than the average adult.
Speaking at a news conference in Brussels, Barnier said: 'It is then we shall see whether agreement we are hoping for is in our grasp.
The Prime Minister has faced growing pressure over her Brexit plan - which has come to be dubbed as the "Chequers Plan" (after the location at which it was forged) that would result in Britain maintaining a common rulebook for goods, including agricultural products, with the European Union after Brexit.
First, they would discuss how much detail to bind the European Union and Britain to in a political declaration to accompany the withdrawal treaty, laying out the shape of a future relationship on trade, security and other matters.
Mr Barnier's comments came after Taoiseach Leo Varadkar had earlier told the Dail in Dublin: "I do not anticipate there will be any change to the EU's position or any change to our negotiating guidelines".
"The government's urgent priority must be to secure a withdrawal agreement.
I think that the alternative to that will be not having a deal".
However, pro-Brexit Conservative MP Andrew Bridgin poured scorn on the IMF's analysis saying that the IMF had been wrong before, and were so again: "Christine Lagarde, the same IMF, who told us that if we even voted we would be in an immediate recession, it's the same IMF that didn't foresee the economic crash in 2008".
Recent signals from Brussels have buoyed hopes that Britain and the European Union can agree and approve a proper divorce arrangement before it leaves, though the sides are still divided on about one fifth of the details of a deal.
The report on trade volumes between Northern Ireland and Britain was requested by the EU's chief negotiator Michel Barnier as part of the ongoing negotiations over the backstop to avoid a hard land border on the island of Ireland.
A frontier in the Irish Sea has been strongly opposed by unionists who want to avoid any barrier between Northern Ireland and the rest of the UK.
"Our proposal for the backstop on Ireland and Northern Ireland has been on the table since February", Mr Barnier said, switching from his native French to English to get his message over.
The Northern Ireland branch of the Confederation of British Industry (CBI), which speaks on behalf of 190,000 United Kingdom businesses, said that the plan "risks damaging labour shortages".
"For industrial goods there is this well known [trusted trader] system where you don't have to have checks at the border as such", says one member state official who was present, "where you can carry out checks at the place of destination by market surveillance authorities, where the risk is low. We need to de-dramatise the checks that are needed".
"What we need in the withdrawal agreement is a legally operational backstop which fulls respects the territorial integrity of the UK".
A Whitehall source said: "They are clearly accepting that their original solution doesn't work, which is good news, because it means they are considering alternatives and it suggests they will ultimately compromise".
The Brexit deadlock over the Irish border could be broken after Brussels accepted it will need to soften its position to strike a deal with Britain.
"The MAC admit they have ignored the crucial relationship between immigration and trade, and explicitly made no recommendation on whether immigration should be part of the negotiations", she said.
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