Would net migration fall by 100,000 if the UK left the EU?

Nobody knows. It’s an unofficial “ball park figure” for one possible exit scenario and the prediction depends on assumptions which might or might not come true.

Leaving the EU would or could cut net migration by 100,000

Leaving EU 'would cut migration by 100,000' - Migration Watch BBC News, 27 January 2015

Leaving the EU could see UK net migration fall by 100,000 a year, says a new report.

There's no way to know what will happen to net migration following an EU exit. The levels will partly depend on what arrangements the UK negotiates after leaving.

This number isn't so much a prediction of what will happen if we leave the EU as an estimate assuming we adopt a particular policy to restrict low-skilled EU immigration.

There's a lot of uncertainty which is compounded by possible knock-on effects that aren't directly accounted for, such as changes in non-EU immigration and the number of Brits emigrating abroad.

Migration Watch, the organisation behind the report, acknowledges it isn't a precise estimate but a "ball park figure" intended to illustrate the potential of this particular policy.

Assuming we restrict low-skilled EU immigration

Migration Watch says a key objective if the UK leaves the EU should be confining immigration by EU workers to the most skilled workers, who would qualify for a work permit. That’s a question of what policy the UK government adopts, and possibly also what deals might be done in the EU exit talks.

It would mean reducing the number of EU immigrants who would otherwise have come to move into low-skilled work in the UK. That’s where a lot of the 100,000 fall is predicted to come from.

Research has previously indicated immigrants in low-skilled work generally have a marginal economic impact, and immigrants who are young, skilled and working in highly-paid jobs are more likely to have a positive impact on the public purse.

The latest figures, for the year to June 2015, show net EU migration at 180,000. In other words 180,000 more EU citizens came to live in the UK than left to live elsewhere.

The report says that could be more like 65,000 if you restrict low-skilled EU immigration, combined with reductions in student migration, and allow for accompanying family members and some growth over time.

Uncertain even then

The report warns there are a number of reasons why this estimate is inevitably uncertain.

The starting point is to assume that about 70% of immigration and emigration of EU citizens is work-related, and that 20% of them are in high skilled work. These are backed up by analysis of figures for 2004-2014.

That much is fairly uncontroversial. To get a 100,000 reduction you need to decide how much the unskilled portion of these workers will be affected by a new policy, decide how students might be affected, account for family members of workers, and how all these numbers might change in the future.

The report puts figures to these variables, but there's no way to know how accurate any of them will turn out to be, or even if 100,000 is a reasonable 'ball-park' estimate.

Knock-on effects

Even if EU net migration did fall by 100,000 should the UK leave the EU, that isn't necessarily the end of the story. Non-EU migration could change too.

There are currently more immigrants who are non-EU citizens than there are EU immigrants to the UK.

The Migration Observatory at the University of Oxford has suggested employers may try to recruit more non-EU immigrants if it becomes harder to employ EU workers.

This is like a 'balloon effect' which has previously been suggested may have happened in recent years the other way round: restrictions on non-EU immigration leading to increased EU immigration as a knock-on effect.

At the time, though, it was deemed "impossible to determine" whether employers were actively seeking EU workers to deal with the restrictions.

The report mentions that the EU would be likely to reciprocate any restrictive immigration measures adopted by the UK.

This could impact how many British people emigrate abroad, and so introduces another number which could change.

Currently, every year an estimated 130,000 Brits emigrate abroad.