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Long-term migration estimates fail to capture short-term migration trends

12 May 2016

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New analysis released today by the Office for National Statistics (ONS) shows that more National Insurance Numbers were issued to EU migrants than the estimated level of immigration from the EU because of short-term migrants who registered to work, but left the UK after less than a year, The Migration Observatory at the University of Oxford said today.

The analysis was released after concerns were raised about the discrepancy of National Insurance number (NINo) registrations and the estimate of long-term international migration (LTIM) for EU nationals. NINo registrations are substantially higher than LTIM estimates.

National Insurance Numbers (NINOs) are issued to those people who wish to work legally in the UK, or to claim UK benefits, and whose immigration status means that they are permitted to do so. Close to 630,000 EU nationals registered for a NINo in 2015.

The UK’s level of long-term immigration is calculated using data from the International Passenger Survey (IPS). It counts individuals who move to the UK for at least one year. The latest official estimate of overall immigration to the UK was 617,000 in the year to September 2015. During that period, estimated immigration of EU nationals was 257,000.

In a given year, it is possible that significantly more NINos might be allocated to EU migrants than the overall level of immigration from the EU if the NINos are issued to people who remain for less than a year.

Dr Carlos Vargas-Silva, senior researcher at the Migration Observatory at the University of Oxford, said: “Long-term migration estimates fail to capture a range of potentially important changes in migration trends. To provide a more complete picture we would need to monitor a range of indicators that include short-term migration flows. By having a suite of different indicators, public debate could be based on a better understanding of how EU migration is changing in the UK, and what impact various policy changes are really having on migrant numbers.

“The measures that are currently in place to measure international migration all have limitations, so none should be taken as precise on their own – it is always important that we compare several sets of data to create a realistic picture of what is going on.”


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