Status of EU nationals in the UK:

EU nationals who have
lived in the UK for more than 5 years
You do not need to do anything as a result of Article 50 being triggered. Permanent residence status is a right that EU nationals can get under EU law. This will not change while the UK is part of the EU. More information about your right to live in the UK is available on GOV.UK.
EU nationals who have lived in the UK for less than 5 years
You do not need to do anything as a result of Article 50 being triggered. There will be no change to the rights and status of EU nationals living in the UK while the UK remains in the EU. More information about your right to live in the UK is available on GOV.UK.
EU nationals who are planning to visit or live in the UK
EU nationals continue to have a right to enter and live in the UK. There will be no change to the rights and status of EU nationals living in the UK while the UK remains in the EU.