What's next for Brexit? A timeline of the U.K.'s departure from EU

Prime Minister Theresa May triggered Britain's withdrawal from the European Union under Article 50 of the EU's Lisbon Treaty on Wednesday. The departure process is expected to last two years.

It's important to keep in mind, however, that no country has ever departed the EU since its early beginnings asthe European Economic Communitywith just six member nations in 1957.Britain has been a member since 1973 and disentangling those 43 years of treaties and agreements is a complex business.

That's why Chancellor of the Exchequer Philip Hammondhas said the process is more likely to take four to six years.

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Here is an approximate timeline of events, based on a mixture of public information and estimations by EU sources:

March 29: The Trigger

Tim Barrow, Britain's top envoy to the EU,visited the European Council building around the corner from the embassy in Brussels anddelivered May's signed letter giving notice to quit thebloc to EU summit chair Donald Tusk. In London, May gave an address to a rowdyand divided Parliament.

March 31: Summit, guidelines and recommendations

Within 48 hours after reading the letter, Tusk will send the 27 other states draft negotiating guidelines. He will outline his views in Malta, where he will be attending a congress of centre-right leaders. Envoys to Brusselsfrom those 27 nations will meet thereto discuss Tusk's draft.

April 11: Advisers weigh in

Government EU advisers, often referred to as "sherpas,"from each of the remaining 27 EU nations are expected to meet in Brussels to discuss guidelines. They are expected to meet again on April 24 for further revisions.

April 27:EU affairs ministers gather

Also from the 27 nations, the General Affairs Council (GAC) willmeet in Luxembourg to prepare EU27 summit.

April 29:Negotiator is appointed

EU27 leaders will meet in Brussels to agree on guidelines and mandate Michel Barnier as chief negotiator.

May 2: Barniermakes recommendations

After the May Day holiday, Barnieris expected to go back to council with his recommendations for how negotiations should be structured, seeking the governments' approval.

May: Directives established

The GAC will meetto agree on legal "negotiating directives" to bind Barnier. The GAC has a routine meeting scheduled on May 16 but could gather to discuss the matterat any time.

June: Parties meet face-to-face

Approximately a yearafter theJune 23 referendum vote that brought about Brexit, British negotiators led by David Davis will sit down with Barnier's EU team. This meeting could, however,happen anytimeafter the April 29 EU summit. Full negotiations must wait until EU governments sign off on the directives, but both can save time by fixing procedural arrangements who will meet whom where, speaking what language, and so on once Barnier has a mandate. Once the 27 governments have signed off on the directives, negotiating teams will start talks, each tackling certain areas.

December 2017:Divorce deal drawn up?

Brussels wants a basic deal on a Withdrawal Treaty by the end of the year. Key issues includethe exit bill for Britain's outstanding commitments,treatment of British and EU expats,outstanding EU legal cases andnew border rules.

Early 2018: Exploringnew relationships

May wants to negotiate a comprehensive free trade deal. Few see two years as enough time to agree on one and Brussels wants to hold off starting talks until after Brexit is complete. But London and some EU states may push for parallel trade talks. Most diplomats expect some synthesis of the two approaches.

October 2018: Finalize the Withdrawal Treaty

Barnierhas targetedOctober in orderto allow time for ratification by the European Parliament and a majority in the European Council by March 2019.

Autumn 2018 to Spring 2019: Scottish independence vote

The Scottish government wants an independence vote and voted March 28 to supportone. ButMay has so far rejected the call for a second Scottish referendum until after Britain leaves the EU.

March 29, 2019: Britain'sofficial exit

On the two-year anniversary of the presentation of May's Article 50 letter, the U.K. will have met its contractual obligation to allow two years to negotiate an exit.The U.K.'s exit. As it happens,Friday, March 31, 2017is the last business day of the quarter, so that date could be fine-tuned. Britain could leave earlier if it gets a deal, and the two-year deadline can be extended if all agree. But Brussels wants Britain out before EU elections in May 2019.

2019 and beyond: transition period

May and EU leaders say transitional arrangements may well be needed, to give more time to agree on a future trade deal and give people and businesses time to adjust to the divorce. Many see another two to five years after Brexit for a final settlement. If Scotland votes for independence, expect more years to negotiate its split from London and possible re-entry to the EU.

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