The message from Prime Minister Theresa May seems straightforward enough: Brexit means Brexit. But what does this actually mean about the future status of the three million EU citizens currently living in the UK?

While Mrs May has been cautioned by key figures including Scotland’s First Minister Nicola Sturgeon and the Mayor of London Sadiq Khan not to use EU nationals living here as a bargaining chip for Brexit negotiations, she has so far refused to give any guarantees on this point. This issue will not be dealt with until the status of UK citizens living on the continent comes on the agenda during negotiations. There are also concerns guaranteeing a right to remain would risk a huge new movement of EU nationals into Britain.

Given the impasse, what are the potential options that are likely to be explored by the UK Government in addressing this very important and emotive issue? Is it also possible to develop a solution on both the status of existing EU nationals and future immigration from the continent in Scotland given the different outcome in the referendum result north of the border?

Firstly the withdrawal negotiations will take at least two years to conclude and, in that time, the free movement of EU nationals into the UK will continue.

The longer term position is much less clear and will depend on the relationship ultimately agreed with the remaining member states. There are a number of possible outcomes but it should be noted there is no precedent for a European country to secure access to the EU single market without being subject to free movement of its people.

The UK might opt to join the European Economic Area (EEA), as countries such as Norway, Liechtenstein and Iceland have done, which would allow continued access to the single market. Creating a bilateral agreement with the EU, as in currently in place with Switzerland, is another option. However, unless current rules were amended, these routes would require Britain to continue to accept free movement of EU citizens, a prospect which is highly unlikely to be acceptable to pro-Leave campaigners.

The UK could aim to negotiate a standalone trade agreement with the EU, as the US, Canada and Japan have done. While this would enable Britain to implement its own immigration system, it is far from clear whether the terms of such an agreement would be ideal for British business. This option might however prove more politically acceptable as it could pave the way for a points based system of immigration. What that would mean for the long-term future of EU citizens currently residing here in the UK as well as for the 1.2 million Brits who currently live in other EU states might involve another series of negotiations.

All these considerations, along with the positive impact which immigration has had on the UK’s economy, makes the future status of EU nationals one of the most sensitive issues Mrs May and her colleagues will need to manage in the Brexit negotiations.

It is hoped and anticipated transitional arrangements will be implemented, allowing these individuals to stay in the UK post-Brexit.

Mrs May will also need to carefully consider the situation in Scotland, not only due to the overwhelming vote here in favour of Remain and the potential for this to trigger another independence referendum. Scotland also needs further immigration to support economic growth. If a points-based immigration system was to be implemented in the UK, for example, there may be potential for Westminster to allow some extra flexibility for the Scottish Government to amend the legislation to suit its specific needs.

In this interim period of uncertainty, UK employers of EU nationals have some possible options. They can encourage individuals to consider applying for a registration certificate, permanent residence card or even British citizenship should they meet the relevant criteria.

In the longer term, their future and that of UK citizens living in other EU jurisdictions will be determined by the outcome of negotiations between Mrs May’s team and member states. There’s no immediate need for panic as this will take some time to conclude and, if the residency rights of EU nationals are to change, nothing is likely to happen for at least another two years.

Finlay McKay is a partner and employment law specialist at CMS.