Migration flows Explanatory notes on migration statistics

1. General information

How are migration statistics produced?

Migration statistics are based on a complete count and cover all registered arrivals and departures across municipal or federal borders involving a transfer of the main or sole residence. Their statistical unit is the migration move, not the migrant person. Generally, the number of migration moves is higher than that of migrant persons because a person may move more than once within a year.

Which migration moves are included in the statistics?

Migration statistics cover all registrations, deregistrations and change in housing status recorded by the local registration authorities in accordance with the federal law on registration. An exemption of the obligation to register exists for persons moving to a residence for less than 6 months when they have another registered residence in Germany and for persons moving from abroad for less than 3 months. These cases are consequently not included in the statistics. The obligation to register applies for refugees and asylum seekers, which are included in the migration statistics. It is however not possible to display them separately as immigration motive or immigration status are not part of the statistics.

How are migration moves presented?

Migration statistics show not only the number of arrivals and departures but also the difference between arrivals and departures in the form of net migration. Positive net migration means that more people moved in than out, which is net immigration. Negative net migration means net emigration. The volume of migration is the total of arrivals and departures between two given points in time.

In the publications, a distinction is made between internal, external and total migration. In federal statistics, internal migration covers migration moves between municipalities of a Land and migration moves between Länder. Net internal migration for the whole of Germany is always zero because departures and arrivals within Germany offset each other. In some reference years, however, net migration is not quite balanced, which is due to differences in data processing status between the Land of origin and the Land of destination.

External migration statistics cover arrivals and departures across the borders of Germany (or across the borders of the former territory of the Federal Republic). Total migration consists of internal migration and external migration.

Migration moves can be represented as migration flows at various geographical-administrative levels. The territory of origin and the territory of destination are defined and for each of them, individual areas or a regional level can be chosen. Here are examples where individual areas have been selected:

  • arrivals from Land A to Land B
  • arrivals from country X to Land A
  • departures from Land A to country X

Where regional levels are examined, migration moves are categorised by border crossed (municipality, administrative district, administrative region, Land or Germany). Here are examples of migration flows shown in migration statistics:

  • across Land border (territory of origin)
  • across Land border (territory of origin) to another Land (territory of destination)
  • across federal border (territory of origin) to another country (territory of destination)
  • etc.

2. Key figures of migration statistics – migration rate

The migration rate reflects - for a reference year and a given territory - the migration moves per 1,000 people of the average population of that territory. It is well suited for comparisons over time and regional comparisons as it takes account of the size of the reference population.

Migration rates may by classified by age, sex or citizenship and can be calculated for subpopulations. As some groups (foreign population, young adults) often have higher mobility, it may be useful to perform studies on the mobility behaviour of different groups or on their impact on the population structure.

3. Distinguishing between citizenship and country of origin

The “country of origin” variable used in migration statistics is often confused with the “citizenship” variable. The two variables are not identical. Citizenship means that a person legally belongs to a specific state and is indicated in the passport. The country of origin refers to the country in which the person last lived. For example, someone with Polish citizenship who last lived in France and now registers in Germany has “Poland” as value for the variable "citizenship" and “France” as value for "country of origin".

4. Administrative deregistration and “deregistration with new residence unknown”

People moving out of a residence without taking a new residence in Germany are obliged to deregister. In many cases, however, people move out without deregistering. If a registration office discovers that a person no longer lives at the address she is registered at, it may perform an administrative deregistration. Administrative deregistrations are generally included in the external migration statistics.

If the registration office does not know where a person has moved to (for example, because a voter’s notification cannot be delivered), a “deregistration with new residence unknown” is carried out. For foreigners, the country of citizenship is in this case generally entered as territory of destination. Where this is not meaningful (for refugees for example), and where Germans are concerned, the value “no data provided” is entered in the variable territory of destination.

Since reference year 2015, tables on external emigration have been available separately by type of deregistration (regular or administrative deregistration).

5. Reference periods – monthly and annual results

The results of migration statistics are processed and published both monthly and annually. Since reference year 2016, the total of the reference months have formed a provisional annual result for the reference year, which differs from the final result for the reference year due to methodological reasons. The reason for the differences is that registration offices sometimes correct their previous information on migration moves; such corrections are then integrated into the annual result.

6. European migration statistics

European migration statistics based on EC Regulation 862/2007 are not comparable with the results of national migration statistics. German migration statistics cover migration moves irrespective of any minimum duration of stay, while European migration statistics include only persons who moved their usual residence for at least 12 months (long-term migrants). To be able to estimate such long-term migrants on the basis of the data available, estimation methods have been developed for Germans and foreigners.

7. Accuracy of migration statistics

Since migration statistics are based on a complete count, overall quality is considered as good. Nevertheless, it depends on the accuracy of the data supplied and especially on whether people obliged to register comply with that obligation. On the whole, the coverage of arrivals is more reliable than that of departures because people mostly register when arriving but more frequently fail to deregister when moving abroad. Although part of such missing deregistrations are replaced by administrative deregistrations carried out by the registration offices, it is not possible to determine for a specific period the exact number of missing deregistrations that remained undetected.

Please also note the current notes on the results of migration statistics.

8. Time series – comparability (geographical and over time)

Data processing is based on a uniform methodology and a uniform procedure, so that the geographical comparability is considered as very good.

However, territorial changes may lead to limited comparability over time. This applies in particular to evaluations at municipality level. For instance, the comparability of the results by municipality or administrative district in a Land with previous year’s data is limited if municipalities were incorporated into larger ones or if there was a territorial reform in the reference year. As changes in larger regional units (e.g. Länder) occur less often, the comparability over time is good at this level. It should be noted that results up to reference year 1990 refer to the former territory of the Federal Republic and are therefore not comparable with the data as from 1991.

Limitations of comparability over time may also result from register adjustments performed by registration offices that can lead to a higher number of departures due to more administrative deregistrations. This occurred especially in the years 2008 to 2010, when the tax identification number was introduced and the population registers were reviewed all over Germany.