The Annual Population Census is a statistical operation that is published at the end of each year and offers a very detailed snapshot of the population residing in Spain as of 1 January that same year. Its information is broken down to the census tract level, allowing for a very precise analysis of the country.

The census collects the main demographic characteristics of the resident population and also information on labour, education, migration, etc. It has been produced since 2022, and is built entirely from administrative records, based on the Municipal Register. Thanks to this, it is not necessary to send questionnaires to the entire population, which speeds up data collection and reduces costs.

In addition to the Municipal Register, other records are used that provide information on the administrative presence or signs of life of each person, which allows the veracity of their residence in Spain to be assessed. These and numerous other administrative records are also used to construct various census variables relating to people’s characteristics.

The Annual Population Census provides a detailed view of the characteristics of the population residing in Spain as of 1 January of each year. Some of the main information blocks it offers are:

• Demographic characteristics:
  • Distribution by sex and age
  • Nationality
  • Country of birth
• Other relevant features:
  • Educational level
  • Employment situation and economic activity
  • Employment
  • Migratory path and movements
  • Marital status

Furthermore, the Census shows the territorial distribution of the population, with a level of detail that reaches down to the census tract, allowing for a precise analysis by very specific geographical areas.

The Annual Population Census is disseminated in several phases, spread between the months of April and December of each year, following the following schedule for a census referring to 1 January of a given year:

• The first publication is made at the end of that same year, and includes the basic demographic variables.
• The remaining variables are published gradually in the following instalments:
  • April and December of the year following the census year (migration variables and marital status).
  • April and December of the second year after the census year (education and labour variables).

This time lag means that in the same publication, blocks of variables corresponding to censuses from different years are disseminated, which allows the available information to be progressively updated as the statistical work advances.

The Annual Population Census constitutes the official reference population used by all national bodies -ministries, regional statistical offices, the Bank of Spain, universities and research centres-, as well as by international bodies such as Eurostat, the United Nations or the OECD, among others.

Furthermore, it serves as a fundamental basis for multiple areas of analysis and planning, including:

• Regional and public service planning, allowing for the sizing of infrastructure, facilities and resources according to the actual resident population.
• High-precision demographic studies, thanks to the high level of geographical detail and population characteristics.
• Preparation of demographic projections and specific analyses at the municipal and supra-municipal scale.
• Calculation of population rates and indicators. In particular, they constitute the reference denominator of the Basic Demographic Indicators calculated by the INE relating to the phenomena of birth rate, fertility, mortality, marriage and other demographic phenomena.
• Preparation of the Statistics on Migration and Changes of Residence, since it uses the censuses as a starting point
• National Accounts, by serving as an input for macroeconomic estimates related to population.
• Calibration and sample design of surveys, allowing for improved representativeness and accuracy of numerous statistical investigations.

The last Population and Housing Census carried out by the INE was that of 2021, and it constitutes the eighteenth of the historical series. It was part of a global programme promoted by the United Nations and regulated by the EU.

Traditionally, the Population and Housing Census has been the largest and most established statistical operation carried out by the INE. Its purpose was to offer a complete and up-to-date picture of how many people live in Spain, where they live, and what the structural and social characteristics of both the population and housing are. Until the last edition, this operation had been carried out on a ten-year basis.

The Population and Housing Census provided detailed information in three main areas:

• PEOPLE: demographic data (age, sex, nationality and place of birth), migration, educational level, marital status, etc.
• HOUSEHOLDS: household composition and size, housing tenure, forms of cohabitation and kinship relations within the household, etc.
• HOUSING: number, categorization as main and non-main residence (including empty ones), surface area, amenities, conditions, etc.

The 2021 Population and Housing Census introduced a fully innovative methodology, based entirely on the use and statistical treatment of administrative records, which made it possible to dispense with face-to-face interviews and the universal questionnaires typical of traditional censuses. This methodological change represented a substantial advance in efficiency, a reduction of burdens for the general public, and an improvement in the consistency of information.

Thanks to this new way of working, the INE was able to replicate the population operation annually from 2022 onwards, giving rise to the Annual Population Census, which offers an updated and continuous view of the main demographic characteristics.

In short:

• Population and Housing Census:
  • Was a ten-year census.
  • Published until 2021
  • Included information on population, housing, and households.
  • Introduced for the first time the construction exclusively from administrative records.

• Annual Population Census (began in 2022):
  • Produced every year.
  • Since 2022, although their tables also include data from the 2021 Population and Housing Census to facilitate comparison.
  • Only includes the part relating to population (not housing or households).

Furthermore, the new Housing (and Household) Census is scheduled to take place from 2027 onwards, with a reference date of 1 January 2026, and with an estimated periodicity of 3 or 4 years.

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The main database is the Continuous Register, to which numerous administrative records are linked to compile individual information. The main sources are:

• Demographic and social: Municipal Register and Civil Registry.
• Economic and labour-related: General Treasury of Social Security (TGSS), Social Security Institute (INSS), State Public Employment Agency (SEPE), civil servant mutuals (MUFACE, MUGEJU, ISFAS), Spanish Tax Agency (AEAT) and Regional Tax Authorities.
• Educational: Municipal Register, Ministry of Education and Vocational Training, Integrated University Information System (SIIU) and SEPE. .
• Housing: General Directorate of the Land Registry and the regional land registries of Navarra and País Vasco, and the Spanish Tax Agency (AEAT).

The Continuous Population Statistics (ECP) of the INE offers a complete historical series of the resident population in Spain, linking the different censuses and also providing provisional estimates based on the last survey published. Its main contribution is that it allows us to know the evolution of the population on a quarterly basis, even before the next census is published.

In summary, the CPS population series is composed of:

• Population and Housing Censuses (up to 2021) and their intercensal estimates for the intermediate years, with data as of 1 January and 1 July, since 1971.
• Annual Population Census (since 2022), supplemented with quarterly intercensal estimates: 1 January, 1 April, 1 July and 1 October.
• Provisional estimates subsequent to the last available annual census, which allow for temporal continuity.

Since the CPS combines census data with estimates, its level of detail is lower than that offered by censuses. Thus, while the CPS only provides data at the provincial level (since May 2026 data has also been provided for the most relevant municipalities in the country, but only once a year) the annual census provides data at the census section level.

When the highest level of disaggregation or more specific population characteristics are required, it is necessary to resort to the proper census operations:

• Until 2021: Population and Housing Census
• Since 2022: Annual Population Census

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There is information that was obtained through questions in the questionnaire of traditional censuses that is not available in administrative records, despite being useful for statistical research or being contemplated in the European Census Regulation.

To meet this need, in 2021 the Survey of Essential Characteristics of the Population and Housing (SECPH) was carried out for the first time, conceived as a complement to the first Spanish census based entirely on administrative records, to give continuity to the existing census series. It was targeted at approximately 1% of the population.

The SECPH will be carried out every five years from 2021 and provides detailed information on aspects that cannot be obtained administratively, including:

• Daily mobility and travel patterns.
• Detailed kinship relationships between household members.
• Knowledge and use of languages.
• Childcare and care for dependent persons.
• Detailed characteristics of the dwellings and their facilities.
• Information about second homes.
• Detailed building characteristics.
• Other key elements relating to population, households and dwellings.

In summary, SECPH complements censuses by providing qualitative and structural information that cannot be automatically derived from administrative records, thus ensuring that modern censuses maintain the required informational richness at the national and European levels.

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The Municipal Register is an administrative record that lists the residents registered in each municipality. The municipalities are responsible for their creation, maintenance, review and custody and must send variations that occur in their registers (additions, removals and modifications) to the INE every month.

The INE, as part of its competencies, performs the pertinent checks to correct possible errors and duplications. This procedure results in a population figure for each municipality as of January 1.

This figure is submitted by the Presidency of the INE to the Government, following a favourable report from the Registrar Council. The figures are approved at the end of the year by royal decree, which also establishes that the municipal details must be published on the INE website, which disseminates them in the section Official population figures for Spanish municipalities: Review of the Municipal Register.

These figures provide a single total population figure by sex for each municipality, without lower territorial breakdowns (districts, sections or villages) or by other demographic or social characteristics.

For its part, the Annual Population Census is a statistical operation that, based on the Municipal Register, provides the best available estimate of the population residing in Spain on 1 January of each year.

These census figures are the ones that are transmitted to international organisations as the official population figures for Spain and its administrative divisions. (autonomous communities, provinces, municipalities, districts, and census sections).

Although the census is also based on information from the register, it incorporates an additional statistical treatment to correct certain limitations inherent in an administrative record.

• Children under three years of age are included, corresponding to births already registered in the Civil Register, but who have not yet been able to be included in the register because the necessary checks have not been completed.
• Although the register applies renewal and verification procedures for the foreign population, the census adds additional treatments based on the so-called "signs of life" methods, which are internationally recommended. These consist of assessing the probability that a person actually resides in Spain by cross-referencing information from different administrative records related to labour, education, benefits or taxes.
  This methodology makes it possible to detect situations in which a person is still listed in the register, but probably no longer resides in the country, and vice versa.
  Likewise, these techniques are used to identify very rare cases of extremely elderly people (centenarians or even people over 110 or 120 years old) who remain on the register due to administrative errors, generally related to deaths that were not properly registered decades ago. In these few cases, the entry remains active in Municipal Register and the person artificially "ages" in the system.
  Although these situations are infrequent, the census includes specific checks on the population aged 100 years or over to ensure the quality of the statistics.

In any case, the numerical differences between the two operations are generally very small, since the census is based on the register itself and both are based on the same administrative information system.

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The statistical operation Nomenclature. Population per population unit offers a detailed list of the entities and population centres existing on 1 January in each municipality, including their codes and their populations as of that date.

It is obtained from the updating of population centres and entities that the municipalities do in their municipalities and which, in compliance with current legislation, they convey to the INE at least once a year.

As of 1 January 2024, populations are calculated from information from the Annual Population Census, so their results are fully consistent with the results of this operation at all administrative levels and also their breakdowns by sex and age.