It is officially the start of Brexit. Theresa May, the British Prime Minister, confirmed that the UK government has formally served Article 50 of the Lisbon Treaty on the European Union, signaling the divorce of a 44 year relationship. This is the beginning of a legal process that should end in two years.

But what happens now?

Article 50 of the Treaty of Lisbon gives any EU member the right to leave. The leaving country has two years to negotiate an exit deal and once it’s set in motion it can’t be stopped except by unanimous consent of all member states. No country has ever left the EU before, a process that’s likely to be lengthy and complicated.  The exit deal must be approved by a “qualified majority” of EU member states and can be vetoed by the European Parliament.

Triggering Article 50 starts the clock running. After that, the Treaties that govern membership no longer apply to Britain. The terms of exit will be negotiated between Britain’s 27 counterparts.  The hardest part will be agreeing to new trading relations and negotiating free movement, which could take another five years.

Business leaders want the easiest terms possible, to prevent economic harm.  This historic moment cannot be turned back. Britain is leaving the European Union.