By David Phinnemore, Queen’s University Belfast

Now that Theresa May, the British prime minister, has triggered Article 50, the process of formally negotiating Brexit can begin. Here’s what to expect in the next two years.

First, the EU-27 will acknowledge the notification. The EU-27 will then focus on adopting “guidelines” for the negotiations. Determining these will be the responsibility of the European Council, so the leaders of the EU-27 member states, the president of the European Commission, Jean-Claude Juncker, and the European Council president, Donald Tusk.

Preparing the EU 27 for negotiations

To adopt the guidelines, the European Council will meet – minus the UK – in extraordinary session on 29 April 2017.

The guidelines are expected to set out some basic principles, including the need to accept the free movement of goods, services, capital and people for access to the single market. They will also set out the issues that the EU 27 will insist are covered in the withdrawal agreement. That will include: the UK’s financial liabilities, so money it owes, for example, to cover the pensions of EU officials; the rights of EU citizens currently in the UK; transitional funding arrangements; and the nature of the new EU-UK frontiers – particularly the land border in Ireland.

The guidelines will also confirm who will be negotiating on behalf of the EU-27 – which means they will make formal the role of Michel Barnier as the European Commission’s chief negotiator. They will set out where negotiations will take place (Brussels); and the sequence of negotiations.

Once the guidelines have been adopted, attention will shift to the EU-27 in the Council and the adoption of the formal mandate for negotiations. This will provide Barnier and his taskforce with the detailed instructions they need to carry out negotiations with the UK.

Negotiations

With the mandate adopted – probably not until late May 2017 – negotiations will be opened. For the UK, these will be led by David Davis, Secretary of State for Exiting the European Union. Day-to-day negotiations are expected to be led by the permanent secretary in the Department for Exiting the European Union (DExEU), Oliver Robbins.

The UK government is eager to see the negotiations focus from the outset on the future, post-Brexit UK-EU relationship. It is the EU-27, however, that will determine the sequencing of the negotiations.

The EU’s priority is determining the terms of withdrawal, including any UK financial liabilities. It will only be willing to move on to talks about future UK-EU relations once these terms have been broadly agreed. The new relationship will be the subject of a further set of negotiations which formally cannot begin until the UK has left the EU.

Reaching agreement and securing approval

Article 50 envisages two years for agreeing the terms of the UK’s withdrawal. Whether this will be sufficient remains to be seen. Much will depend on whether and to what extent the EU-27 can reach agreement among themselves.

Formally, only a qualified majority of member states – 20 member states representing 65% (289.5m) of the population (445.5m) of the EU-27 – is required. In practice, it is expected that the EU-27 will proceed on the basis of consensus.

The option does exist to extend the two-year period, although this would require unanimous agreement of the EU-27 and the UK.

The negotiations proper cannot, however, last the full two years. Sufficient time needs to be set aside, once political agreement has been reached on the terms of withdrawal, for the definitive legal text of what has been agreed to be drawn up and finalised. That text will also need to be translated into each of the EU’s other 23 official languages and those versions of the text agreed.

There will then be a signing ceremony before the terms of withdrawal are presented to the European parliament for its “consent”, which requires a simple majority of MEPs to vote in favour.

The agreement will also be considered by the UK parliament, where both houses will have a vote on whether to adopt it or not. The UK government has committed to holding these votes before the European parliament debates the agreement.

Finally, assuming the European parliament votes in favour of the terms agreed by the House of Commons and House of Lords, the EU-27 will, through a qualified majority vote in the European Council, formally “conclude” the terms of withdrawal. The UK will then leave the EU on the date on which the agreement enters into force. That date could be one beyond the initial two years for negotiation set out in Article 50.

If no agreement is reached within the two years and there is no agreement to extend the two-year period, the EU treaties will cease to apply to the UK two years after the date the British prime minister issues the notification of intention to withdraw. The UK’s membership of the EU will simply lapse.

With notification on March 29 2017 and allowing a month for each of the various post-negotiation stages, agreement will have to be reached on the terms of withdrawal and any transitional arrangements in preparation for the new post-Brexit UK-EU relationship by November 2018 if the whole process is to be wrapped up within the two years provided for in Article 50.

Barnier has indicated he wishes to see the negotiations completed by October 2018. Autumn 2018 will therefore be a crucial period in the negotiations.

Beyond the Article 50 negotiations

The timeframe is extremely tight and may well prove insufficient. Moreover, the UK government will be involved in other negotiations as well.

For starters, it will be looking to begin pre-negotiations on its future relationship with the EU. Simultaneously it will be seeking to establish its own “tariff schedules” with the World Trade Organization so that it can start trade negotiations with third countries and have those deals in place as soon as possible after Brexit.

It will also have to negotiate with the devolved administrations in Belfast, Cardiff and Edinburgh about what happens to powers that will be “repatriated” from the EU.

Triggering Article 50 sets the clock running for the Brexit negotiations. It is the start of an unprecedentedly challenging period.

David Phinnemore, Professor of European Politics, Queen’s University Belfast

This article was originally published on The Conversation. Read the original article.