The European Commission is telling states to "step up preparations" for all outcomes
The European Commission has issued a new document on the preparation for Britain's exit from the EU.
It notes that "no progress" has been made in agreeing a 'backstop' to avoid a hard Irish border.
It is calling on member states, including Ireland, to "step up preparations" following a request last month by the by the European Council to intensify preparedness at all levels and for all outcomes.
It says: "While the EU is working day and night for a deal ensuring an orderly withdrawal, the UK's withdrawal will undoubtedly cause disruption - for example in business supply chains - whether or not there is a deal.
"As there is still no certainty that there will be a ratified withdrawal agreement in place on that date, or what it will entail, preparations have been ongoing to try to ensure that the EU institutions, member states and private parties are prepared for the UK's withdrawal.
"And in any event, even if an agreement is reached, the UK will no longer be a member state after withdrawal and will no longer enjoy the same benefits as a member.
"Therefore, preparing for the UK becoming a third country is of paramount importance, even in the case of a deal between the EU and the UK."
It adds that the withdrawal "is not only the responsibility of the EU institutions".
"It is a joint effort at EU, national and regional levels, and also includes in particular economic operators and other private parties - everyone must now step up preparations for all scenarios and take responsibility for their specific situation."
But it says: "While progress has been made, important issues remain open, including the continued protection, in the United Kingdom, of the 'stock' of geographical indications protected in the United Kingdom while it was a member state and the standards of the protection of personal data transmitted to the United Kingdom while it was a member state.
"Also the issues related to ongoing police and judicial cooperation in criminal matters remain open.
"In addition, issues surrounding the governance of the Withdrawal Agreement, including the role of the Court of Justice of the European Union, are still unresolved.
"Finally, no progress has been made in agreeing on a 'backstop' to avoid a hard border on the island of Ireland, independently of the outcome of the negotiations of the
The document outlines two possible main scenarios:
This is referred to as the "no deal" or "cliff-edge" scenario.
The communication says: "Preparing for the withdrawal of the United Kingdom from the European Union, in whatever scenario it may take place, is a matter for everyone.
"The withdrawal will change the relationship and will have significant effects for the citizens and businesses of the EU of 27 member states, some of which cannot be remedied.
"It is therefore important to take the necessary action in time and that everyone - citizens, businesses, member states and EU institutions - take the necessary steps to be ready and to minimise the negative impact that the withdrawal will have."
The Commission is asking the European Parliament and Council to give "priority treatment" to legislative proposals that are related to the withdrawal - so that the acts can be in force by the withdrawal date.