5. Migration Assumptions, 2010-Based National Population Projections

Introduction

The 2010-based national population projections are based on the estimated population at the middle of 2010 and a set of demographic assumptions about future fertility, mortality and migration based on analysis of trends and expert advice. This report provides detailed information on the principal and variant migration assumptions used in the 2010-based national population projections. The new long-term assumption for net migration to the UK is +200,000 each year, compared with +180,000 a year in the 2008-based projections.

Migration assumptions

Assumptions of future international migration have been derived from analyses of recent trends in civilian migration to and from the UK. Migrants are defined as individuals who change their country of usual residence for a period of at least one year, so that the country of destination becomes the country of usual residence.

International migration figures are derived from a number of sources. The principal source is the International Passenger Survey (IPS). Adjustments are made to account for people who enter or leave the country initially for a short stay but subsequently decide to remain for one year or more ('visitor switchers'), and people who originally intend to be migrants but in reality stay in the UK or abroad for less than one year ('migrant switchers').

The IPS also excludes most, but not all, people seeking asylum. Estimates of the net flows of asylum seekers (and their dependants) not captured by the IPS are obtained from Home Office data.

Since the last projections round, the Migration Statistics Unit (MSU) at ONS has made two adjustments in the methodology to produce long-term international migration estimates. They relate to Northern Ireland and the Republic of Ireland.

Northern Ireland

From 2008, the ONS migration estimates no longer use IPS data for Northern Ireland and instead use data from NISRA. In addition - since NISRA data incorporates visitor and migrant switchers, asylum seekers and Republic of Ireland flows in their data - the adjustments/ assumptions for these components will be at Great Britain (GB) level for the 2010-based projections.

Republic of Ireland

Estimates of flows between the UK and the Republic of Ireland are based on the Irish Quarterly National Household Survey and the National Health Service Central Register (NHSCR) and are agreed between the Irish Central Statistics Office and ONS. The IPS figures (for data from 2008) now incorporate the ROI, but there is a discontinuity between 2008 and earlier years as revisions to back series have not been run. Therefore, the NPP team have decided to exclude ROI flows from the IPS data and continue to base their assumption of ROI flows on Central Statistics Office (CSO) data until there is a longer time series.

Long-term assumptions

Long-term assumption for the UK

Table 5-1 shows the long-term assumptions for the 2010-based projections of future net international migration to the UK broken down by component category and compares them with the assumptions used for the 2008-based projections. The long-term international migration assumptions in the 2010-based projections take effect from 2016-17.

Table 5-1

Long term annual net migration assumptions by component, United Kingdom, 2016-17 onwards

Table source: Office for National Statistics

The new long-term assumption for net migration to the UK is +200,000 each year compared with +180,000 a year in the previous projections. This increase in net migration is due to the inclusion of two more years of data. Annual net migration of +200,000 is in line with the average levels of net migration in recent years. Final international long-term estimates for 2010 were not available when these long-term assumptions were decided; these estimates are scheduled for publication on 24 November 2011.

Long-term assumptions for individual countries

The breakdown of the long-term net international migration assumption between the four countries within the UK is shown in Table 5-2 below. This table also shows the assumptions made about cross-border migration between the constituent countries of the UK which are derived from analyses of trends in cross-border flows as estimated from the National Health Service Central Register (NHSCR).

Table 5-2

Long term annual net migration assumptions, United Kingdom and constituent countries, 2016-17 onwards

Table source: Office for National Statistics

Short-term assumptions

Short-term assumptions

Special assumptions have been applied for the first few years of the projections (2010-11 to 2015-16). These were decided after the long-term assumptions, thus enabling them to take account of the most up to date data available. The breakdown of these assumptions is shown in Table 5-3. These short-term assumptions differ from the long-term assumptions for the following four reasons:

1. The assumptions for 2010-11 take account of provisional estimates of long term international migration (LTIM) for 2010 and additional provisional migration data, from the NHSCR, for the second half of 2010.

2. An allowance has been made for additional net migration totalling +120,000 over the five years from 2011-12 to 2015-16 from the accession countries which joined the European Union in May 2004 (the A8 countries - the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Slovakia and Slovenia) and January 2007 (the A2 countries - Bulgaria and Romania). Net migration from the countries which joined the EU in May 2004 is estimated to have fallen in 2008-09 followed by an increase in 2010. (see Figure 2.2, Migration Statistics Quarterly Report). The projections assume that net migration from the accession countries will decline from +40,000 in 2011-12 to net zero in the long term. Note: The accession country component was not separately identified for the first year of the projection (2010-11).

3. The figures for the first three years of the projection (2010-11 to 2012-13) assume a gradual transition from current cross-border migration levels to the assumed long-term levels (from 2013-14).

4. An allowance has been made for the return of 2,000 Armed Forces (including dependants) from Germany to the UK during the period 2012-13 to 2015-16. They have all been assumed to return to England.

Table 5-3

Short-term annual net migration assumptions, United Kingdom and constituent countries, 2010-11 onwards

Table source: Office for National Statistics

Table notes:

1. Including accession countries.
2. This comprises the A8 countries which joined the EU on 1 May 2004 (the Czech Republic, Estonia, Hungary,Latvia, Lithuania, Poland, Slovakia and Slovenia) and the A2 countries (Bulgaria and Romania)which joined the EU on 1 January 2007.

Figure 5-1 shows the total net migration to the UK between 1991-92 and 2020-21.

Figure 5-1

Total net migration, United Kingdom, 1991-92 to 2020-21

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The equivalent figures for the constituent countries of the UK can be found in the appendix.

Figure 5-2 shows the total net migration for the constituent countries of the UK between 1991-92 and 2020-21.

Figure 5-2

Migration assumptions for the individual countries of the United Kingdom

Total net migration 1991-92 to 2020-21

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Age and sex distribution

Table 5-4 and Figure 5-3 show assumed long-term annual net migration by age and sex for the UK from 2016-17 onwards. Equivalent information for in- and out-migration are given in tables 5-5 and 5-6 respectively.

Table 5-4

Assumed annual long-term net migration by age and sex, United Kingdom, 2016-17 onwards

Table source: Office for National Statistics

Table 5-5

Assumed annual long-term in-migration by age and sex, United Kingdom, 2016-17 onwards

Table source: Office for National Statistics

Table 5-6

Assumed annual long-term out-migration by age and sex, United Kingdom, 2016-17 onwards

Table source: Office for National Statistics

The equivalent tables for net, in- and out-migration for the constituent countries of the UK can be found in the excel download.

Figure 5-3

Long-term annual net migration by age and sex, United Kingdom, 2016-17 onwards

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The equivalent figures for the constituent countries of the UK can be found in the appendix.

Assumptions for migration variants

Table 5-7 shows the assumed long-term annual net migration for the standard variants for the UK and its constituent countries.

Table 5-7

Assumed long-term annual net migration for the standard variants and special case scenario

Table source: Office for National Statistics

In the standard variants, the long-term levels are assumed from 2016-17 onwards. The high and low migration variants are 'non-additive', that is, the UK assumptions in these variants are not equal to the sum of those in the corresponding variants for the four individual countries. More information can be found in the 2010-based national population projections background and methodology report, in the section, relationship of UK level projections to individual country level projections.

Figure 5-4 shows actual and assumed net migration to the UK between 1991-92 and 2020-21 by principal projection and high and low variants.

Figure 5-4

Actual and assumed total net migration, United Kingdom, 1991-92 to 2020-21

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The equivalent figures for the constituent countries of the UK can be found in the appendix.

Background notes

1. Details of the policy governing the release of new data are available by visiting www.statisticsauthority.gov.uk/assessment/code-of-practice/index.html or from the Media Relations Office email: media.relations@ons.gsi.gov.uk

   These National Statistics are produced to high professional standards and released according to the arrangements approved by the UK Statistics Authority.

Appendix A: England charts

Figure 5-1

Total net migration, England, 1991-92 to 2020-21

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Figure 5-3

Long-term annual net migration by age and sex, England, 2016-17 onwards

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Figure 5-4

Actual and assumed total net migration, England, 1991-92 to 2020-21

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Appendix B: Wales charts

Figure 5-1

Total net migration, Wales, 1991-92 to 2020-21

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Figure 5-3

Long-term annual net migration by age and sex, Wales, 2016-17 onwards

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Figure 5-4

Actual and assumed total net migration, Wales, 1991-92 to 2020-21

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Appendix C: Scotland charts

Figure 5-1

Total net migration, Scotland, 1991-92 to 2020-21

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Figure 5-3

Long-term annual net migration by age and sex, Scotland, 2016-17 onwards

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Figure 5-4

Actual and assumed total net migration, Scotland, 1991-92 to 2020-21

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Appendix D: Northern Ireland charts

Figure 5-1

Total net migration, Northern Ireland, 1991-92 to 2020-21

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Figure 5-3

Long-term annual net migration by age and sex, Northern Ireland, 2016-17 onwards

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Figure 5-4

Actual and assumed total net migration, Northern Ireland, 1991-92 to 2020-21

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