After five years of policies intended to reduce immigration, recently released figures from the Office for National Statistics show that net migration has reached the second highest level on record and that EU migration made up more than half of immigration to the UK. As the EU membership referendum approaches, the free movement of people is a key topic for both the Remain and Leave campaigns.

The Leave campaign argues that leaving Europe is the only way to reduce migration, while the Remain campaign argues that Brexit could have relatively limited effects on immigration to the UK.

The potential impact of Brexit

The greatest challenge in assessing the impact of Brexit on immigration is the unknown consequences of the vote, namely what relationship would replace EU membership following a UK exit.

Access to the single market

It is possible that the UK’s membership of the EU would be replaced by an association agreement that included liberal access to the single market and therefore, continued free movement. If this happened, the effects of Brexit on EU migration to the UK could be relatively limited. The Norwegian and Swiss models of EU association illustrate that accepting the principle of EU free movement of people may be the price the UK has to pay in order to gain access to the single market.

The UK-EU negotiation might be different from models agreed with other states previously but it is reasonable to assume that free movement of people will be one of the areas discussed in any negotiations to allow the UK access to the single market.

Immigration policy

A withdrawal of the UK from the EU could potentially mean the end of free movement and the introduction of admission requirements for EU citizens who want to live and work in the UK. As a result, EU citizens may face the same immigration rules as non-EU citizens, either needing to qualify for work or family visas. Such rules would make it more difficult for EU citizens to live and work in the UK legally.

Indeed, the Social Market Foundation (in partnership with Adecco Group UK & Ireland) conducted a study that concluded that 88% of EU migrants currently working in the UK would not qualify under the current visa rules that apply to migrants from outside the EU.

This is because the minimum annual salary for qualifying to work in the UK under a Tier 2 (General) visa is £20,800 (or more, depending on the role) and individuals who want to bring their spouse to the UK under a family visa need to meet the family income threshold of £18,600 (or more if dependent children are included in the application).

If the same immigration rules were to apply to EU citizens, then the make-up of the UK workforce could look very different in the future.

The potential impact of remaining in the EU

David Cameron has sought to renegotiate the UK's relationship with the EU and so, even if the UK remains in the EU, there will be changes – a number of which will have implications for the free movement of people and immigration to the UK.

The changes themselves are not to the principle of free movement of people but are changes to eligibility for benefits, which could have a deterrent effect on any EU nationals considering a move to the UK. These changes include:

Emergency brake

For seven years an "emergency brake" can be applied. This would restrict EU migrants' access to in-work benefits for the first four years after they arrive in the UK. After the seven year period, the UK would then have to gain the approval of the European Commission and EU member state governments to apply a brake for any further period.

Out of work benefits

The power to deny benefits to out of work EU migrants, and deport migrants who have been unable to find employment after six months and are not self-sufficient, have been negotiated.

Child benefit

Child benefit can be reduced to the level of the migrant's home EU country. This would apply to new arrivals immediately but could also apply to existing recipients from January 2020.

These changes could have an effect on the attractiveness of working in the UK and so could also lead to a shift in the make-up of the UK workforce.

Immigration is the aspect of the EU referendum that is currently attracting most attention. A vote to leave the EU would certainly have an impact on the way in which people come to live and work in the UK. If we choose to leave, there will be a period of negotiation as to what the future of immigration into the UK from Europe will look like and this could involve having to accept freedom of movement. However, a vote to stay in the EU could also have consequences for immigration to the UK, which could affect many people already working in the UK and their employers. If we vote to remain, it will be interesting to see how many of the measures negotiated will be introduced and how quickly.