Belgium METHODOLOGY

Belgium uses Statbel's origin classification, which combines current nationality, first registered nationality and the first registered nationality of both parents. The selected model includes non-Belgians and Belgians with a foreign background, including the published mixed-parental-background group. Naturalised persons consequently remain identifiable by origin. Because the classification is based on registered origin rather than only birthplace, it may retain parts of the third generation.

The broad version was selected because it is the most inclusive official origin measure available with a usable population breakdown.

The 2026 population is divided using Statbel's official origin categories. Non-Belgians are available by individual age and sex. Belgians with a foreign background are available in broader age groups and are distributed within those groups using the corresponding population structure by sex.

Fertility is differentiated by the mother's citizenship. The rate observed for foreign citizens is applied to the broader migration-background population, which also includes Belgian citizens with a foreign background. The same age- and sex-specific mortality schedule is used for both populations.

Baseline immigration and emigration are derived from average gross flows for 2015-2024 and classified by country of birth. The flow definition therefore differs from the nationality-and-origin definition of the starting population.

• The population, fertility and migration inputs use the official origin, citizenship and birthplace classifications available for each component.
• Belgians with a foreign background are published in broad age groups, which are distributed to individual ages within those groups.
• The origin definition can retain parts of later generations and consequently has a broader generational reach than definitions based only on birthplace.
• The fertility rate for foreign citizens serves as the available proxy for the broader population with a foreign background.

• Starting migrant share: 36.6%
• Baseline tipping point above 50%: 2044
• Reverse tipping point below 5%: 2099

• Statbel: Origin, accessed 28 September 2026.
• Statbel: Population by residence, nationality, age and sex, accessed 28 September 2026.
• Statbel: Natality and fertility, accessed 28 September 2026.
• Statbel: Life expectancy and life tables, accessed 28 September 2026.
• Eurostat: Immigration and emigration by country of birth, accessed 28 September 2026.