Driven by data; ridden with liberty.
The Office for National Statistics (ONS) has published a note on discrepancies between the long-term international migration figures – estimated by the International Passenger Survey (IPS) – and the count of National Insurance Number (NINo) registrations for EU citizens .
The note found short-term migration “largely accounts” for the recent differences between the migration statistics and the NINo registrations . The note also stated the IPS remains the best available source for measuring long-term international migration.
There are fundamental differences in definitions between these two sets of figures, so it is not possible to add and subtract different categories to make them align. For instance, people who come to this country may be unable to register for an National Insurance Number, such as children, or may register years after they have arrived. NINo registrations are not a measure of long-term migration, but do provide insights into migration flows.
This was an initial analysis, and more work will be published in the future.
The note uses short-term international migration (STIM) visit data, including an early release of the latest estimates for mid-2014 of the STIM figures . The full release of this data — along with the Migration Statistics Quarterly Report — will be on 26th May (my birthday – what a present).
The time delay is due to the STIM data being estimated from completed flows: people leaving. The IPS is not just asked to those who arrive, but those who leave the country too.
This sum is meant to be illustrative of the flows into Britain, but is not intended as a formal measure of migration. The short-term international migration data is based on visits, not people: the same person can be a short-term migrant twice in a year, or even both a short-term and a long-term migrant in the same year. The figures of people making multiple journeys to and from the UK is expected to be small relative to the total flow in a single year, and so will not overly affect the general trends.
A large difference still remains for the EU8 countries (Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Slovakia, and Slovenia). This may be explained by people within categories of migration still not included in this measure, such as those arriving for less than one month, or coming short-term on a basis not meant for work, registering for National Insurance Numbers.
Looking at the Department for Work and Pensions’ Lifetime Labour Market Database (L2), the analysis found “on average 32% of EU8 NINo registrations have interactions that are under 52 weeks”. Moreover:
A further 18% of registrations state they arrived in earlier years to the year in which they registered and therefore should not be counted as an inflow in the registration year.
The Survey of Personal Incomes, produced by the HM Revenue & Customs (HMRC), found that 29% of EU8 nationals who registered for a NINo between 2011/12 and 2013/14 had no interaction at all with the tax, national insurance or tax credit systems.
The Real Time Information (RTI) system, also within HMRC, found for those EU8 nationals that arrived in 2014/15 and interacted with their RTI or Self Assessment systems, around half showed an interaction with the RTI for more than 12 months, and 44% interacted for less than 12 months. A further 6% interacted with the Self Assessment system. As the ONS concludes:
The analysis of NINo activity shows that a substantial proportion (up to 50%) of EU8 citizens have short-term activity of less than 12 months. This supports the evidence from the IPS that the gap between NINo activity and the LTIM series is likely to largely be accounted for by short-term migration.
It should be summarised that the Office for National Statistics has retained its official estimate of long-term migration, which is based on an international definition.
The note suggests that, by adding the short-term visit data to the long-term visitor data, that most of this discrepancy between long-term visitors and National Insurance Number registrations is likely due to short-term migration.
 Masters, A., 2016. Immigration discrepancies. In Defence of Liberty. Available from: https://anthonymasters.wordpress.com/2016/03/23/immigration-discrepancies/ [Accessed: 14th May 2016]
 ONS, 2016. Note on the differences between National Insurance number registrations and the estimate of long-term international migration: 2016. Available from: https://www.ons.gov.uk/peoplepopulationandcommunity/populationandmigration/internationalmigration/articles/noteonthedifferencebetweennationalinsurancenumberregistrationsandtheestimateoflongterminternationalmigration/2016 [Accessed: 14th May 2016]
 ONS, 2015. Short Term International Migration Annual Report Year Ending: Mid 2013 Estimates. Available from: http://www.ons.gov.uk/peoplepopulationandcommunity/populationandmigration/internationalmigration/bulletins/shortterminternationalmigrationannualreport/2015-05-21 [Accessed: 14th May 2016]