The official notification will declare that negotiations should begin as soon as possible, May's spokesman said. "We want negotiations to start promptly but it's obviously right that the 27 have an opportunity to agree their position." he added. As a result, United Kingdom officials have already approached the World Trade Organization to see what they can do in case they cannot reach a deal within the two-year deadline.
European Council President Donald Tusk says he will present draft guidelines for the negotiations on Britain's departure from the bloc within two days of London notifying its intention to leave on March 29.
The government's Brexit negotiating position is ambitious - how would the British public feel if the European Union offered the United Kingdom less favourable terms?
Several other business organisations such as ICAEW and the Confederation of British Industry said they would be commenting on the Article 50 triggering next week, when the process to leave the European Union official starts.
Notification comes 279 days after the referendum of June 23 past year delivered a 52%-48% majority in favour of withdrawal.
Tusk said he would issue draft guidelines for the negotiations within 48 hours, and officials said European Union leaders are then likely to meet at a special summit in early May to approve them.
Both sides would like the early resolution of the status of more than three million Europeans living in Britain, and more than one million Britons living elsewhere in the EU. Ireland's interests are best served by a smooth negotiating process, a transitional deal for trade after 2019 - before a final agreement is reached - and a final deal which allows trade to continue as freely as possible in the long term.
Speculation remains rife in Westminster that May will use the triggering of Article 50 as the springboard to announce a snap general election in May.
Negotiations will begin to outline a UK Brexit deal, which could include trade deals - although this might be handled separately.
"We are going to be out there, negotiating hard, delivering on what the British people voted for", May said on Monday.
Speaking ahead of the visit, Mrs May said: "From my first day on the steps of Downing Street, I made clear my determination to strengthen and sustain the precious Union".
The Scotland head of state is demanding a second referendum on Scottish independence before the terms of Brexit are signed.