1. Main points

  • The migration assumptions are not a forecast or prediction of future migration levels; they should be interpreted as a potential scenario in which future net international migration averages at a certain level.

  • Net international migration in the UK is projected to reach an annual average of 205,000 from mid-2027 onwards (the long-term assumption).

  • Our short-term migration assumptions are effective for the first six years of the projections period up to the year starting mid-2026; over this timeframe, UK net migration averages 232,000 each year.

  • For this national population projections (NPP) release, only a principal projection has been produced; there are no variant projections.

  • This set of NPPs have been developed to meet core user needs, and variant projections are not available as part of the release because of both uncertainty in our mid-year population estimates (the basis of our projections) and uncertainty in setting long-term demographic assumptions following the coronavirus (COVID-19) pandemic.

  • The method used to set the long-term international migration assumptions is based on average annual net-international migration over the preceding 25-year period; this is the same methodology as used in the 2018-based NPPs.

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2. Introduction

This article provides detailed information on the international migration assumptions used in the 2020-based interim national population projections (NPPs). We have published interim NPPs in response to feedback from users and meet core user needs for national-level projections. There is uncertainty in long-term demographic trends arising from the coronavirus (COVID-19) pandemic and statistical uncertainty in our mid-year population estimates. Because of this, we have not produced variant assumptions for the 2020-based interim NPPs. Therefore, for 2020-based interim NPPs, there are principal population projections only and no variant assumptions (for migration, fertility, or mortality) for each UK constituent country and for the UK.

The international migration assumption used in the 2020-based NPPs assumes net international migration to the UK remains constant at +205,000 per year from the year ending mid-2027 onwards; this is referred to as the “long-term assumption”. This assumption is 15,000 higher than the 2018-based principal migration assumption (+190,000).

Demographic behaviour is inherently uncertain and for that reason it is not possible to predict future migration trends. The long-term assumptions should therefore not be seen as forecasts, but rather as a scenario where future net migration averages at a certain level.

Further information on our methodology can be found in Background, methodology and assumption setting: 2020-based interim.

Definition of international migration in the national population projections

The NPPs define migration using the United Nations (UN) definition of a long-term international migrant: someone who has moved to a country other than their usual country of residence for a period of 12 months or more.

The NPP long-term migration assumptions do not include short-term international migrants under the UN definition (that is, those who move to or leave the UK for less than 12 months).

Long- and short-term international migration assumptions

Migration assumptions in the NPPs are split into long- and short-term assumptions.

“Long-term assumptions” take effect from seven years into the projection period, from the year ending mid-2027 onwards.

“Short-term assumptions” are effective from the start of the projections period up to and including the year ending mid-2026. Short-term assumptions are produced using a linear interpolation to join the mid-2020 migration estimates to the long-term assumptions.

Short-term international migration assumption for Northern Ireland

The interpolation of short-term assumptions for Northern Ireland starts from mid-2021, not mid-2020 as for the other UK constituent countries. This is because international net migration for the year ending mid-2020 was -1,800. For more information, please see the 2020 Mid-Year Population Estimates for Northern Ireland release on the Northern Ireland Statistics and Research Agency (NISRA) website. The net international migration observed for the year ending mid-2020 was outside of the long-term average for international migration. Furthermore, preliminary data for part of the year ending mid-2021 suggest a net migration figure closer to recent average figures. Therefore, for Northern Ireland, a net migration figure for the year to mid-2021 has been calculated using an average of the five preceding years (years ending mid-2016 to mid-2020). This has been done because application of the linear interpolation to the long-term assumption starting from the figure for the year to mid-2020 (net migration of -1,800) would lead to a timeseries of net migration loss for many years in the short-term assumption period. This would be outside of the long-term pattern and averages of long-term international migration, which have been observed. Furthermore, the starting point for mid-2021 based on a five-year average better aligns with preliminary migration data for the year to mid-2021, from NISRA. Our linear interpolation for Northern Ireland therefore uses a starting point of mid-2021 and runs to mid-2027 when it transfers to the long-term assumption.

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3. Data sources and methodology

An expert advisory panel was convened to receive advice and feedback on future migration and the development of assumptions.

Our data and methodology remain the same as detailed in the corresponding section in our National population projections, migration assumptions: 2018-based article, except for the following changes.

International migration – changes from 2018-based national population projections

International migration estimates to the UK are based on International Passenger Survey (IPS) data up to March 2020. For the period April 2020 to June 2020, modelled migration estimates were used as the IPS was suspended because of coronavirus (COVID-19). International migration assumption setting was concluded before statistics in the publication Long-term international migration, provisional: year ending December 2020 were finalised. Therefore, migration assumptions do not necessarily reflect the very latest available estimates of long-term international migration, but this is unlikely to materially impact the 25-year average on which the long-term assumptions are based.

Additional flows – changes from 2018-based national population projections

Unlike the 2018-based national population projections (NPPs), the short-term assumptions in the 2020 NPPs do not account for the return of UK armed forces personnel and their dependants. This is because their planned return has already been completed.

Likewise, people granted humanitarian protection who come to the UK from Syria through the Vulnerable Persons Resettlement Scheme (VPRS) are not included because the commitment was met.

The 2020-based NPP short-term migration assumptions take account of the 20,000 Afghan refugees that the UK government has committed to resettle in the UK over the coming five years (from summer 2021). This is through the Afghan citizens resettlement scheme. The 20,000 is in addition to an initial 5,000 planned in the first year.

Cross-border migration – data in use

Cross-border migration (migration between UK constituent countries) is calculated using multiple data sources to derive five-year average rates by single year of age and sex. Data sources are the same as those used in the mid-year population estimates and are as follows:

  • England and Wales – the NHS Central Register (NHSCR) (2016 only) and the Personal Demographics Service (PDS) (2017 to 2020)

  • Scotland – the NHSCR

  • Northern Ireland – Medical Card Register

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4. International migration assumptions

International migration assumptions are held constant from year ending mid-2027 onwards and are referred to as long-term assumptions. Figure 1 shows that the UK long-term assumption for net international migration is +205,000 per year. This is driven by a projected inflow of 533,500 people per year and a projected outflow of 328,500 people per year.

Figure 1 also shows UK short-term assumptions from mid-2020 to mid-2026. These are a linear interpolation from the year ending mid-2020 (UK net international migration of 247,000) to the start of the long-term assumption from mid-2027 onwards.

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5. England charts

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6. Wales charts

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7. Scotland charts

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8. Northern Ireland charts

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Contact details for this Methodology

James Robards
Telephone: +44 (0)1329 444661