We still need to be cautious about Romanian and Bulgarian immigration estimates

This morning the ONS estimated that 212,000 more people migrated to the UK last year than left it, with EU migration in particular under the microscope on the day of the European elections.

However separate government statistics also released today have caused a particular stir among those keen to get a sense of the scale of immigration from Romania and Bulgaria since restrictions on their rights to work in the UK were lifted in January.

The Department for Work and Pensions National Insurance Number (NINo) registrations records show the number of people who have registered with the government to work and pay tax in the UK.

News that the latest figures show that 45,000 more Romanian and Bulgarian nationals gained a NINo between January and March 2014 after the restrictions were lifted could be seen as evidence that more are coming into the country to work. This would be contrary to what ONS labour market statistics found earlier this month, when it was reported that 4,000 fewer Romanians and Bulgarians were employed in the UK.

In both instances however, the figures taken in isolation could be misleading.

The Labour Force Survey - which is the main source of official employment data in this country - asks people to identify themselves as either employed, unemployed or economically inactive. Romanians and Bulgarians working in the country illicitly without a NINo may well show up in the employment figures prior to this January, even if they only registered for a NINo in the first three months of this year.

In other words, those gaining a NINo in the first quarter of this year may have been living and working in the UK long before the transitional controls were lifted. In fact, the government says in its own statistical release that:

"The [Romanian and Bulgarian] NINo registration figures (January to March 2014) are actually reflecting migration over an extended period: the majority of those EU2 nationals registering for a NINo since transitional controls were lifted had arrived in the UK a number of months/years earlier."

Both the ONS and Full Fact have pointed out that employment data isn't necessarily a good proxy for immigration figures. We need figures from the International Passenger Survey to tell us about arrivals, and ONS annual population estimates to give us better figures about population change. Those figures won't be out till August this year and August 2015 at the earliest.