For many centuries, our societies evolved in small village communities: everyone knew each other and could easily identify each other. With the emergence of towns and cities and the increasing mobility of people, it became necessary to be able to identify each person formally and without error. Surnames thus began to appear in the 15^th century; they were definitively established in the 17^th century and written on all records, first religious records and then civil status records (Desabie and Hayoun, 1987). By definition, a person's identity remains the same throughout their life, hence the idea of linking it to birth, with a patronymic name passed down by the family and capital importance placed on the date and place of birth. The need for a system guaranteeing the civil status of each person quickly became apparent in all countries, to avoid problems of identity theft, to ensure that a person cannot contract two marriages at the same time, for example!

With the modernisation of the administrative world, the need to supplement a person's identity with an identifier and the need to store this information in an organised manner have emerged.

In 1941, René Carmille, at that time head of the Department of Demographics and then head of the National Statistical Service, the predecessor of INSEE, started up a first directory with a unique number for each person (then called the national identity number). This directory was established using mechanographic methods based on the civil registers held by the courts. The maintenance of the demographic register was then enshrined in the founding decree of INSEE, from its inception in 1946.

For many years, this register was maintained in a decentralised manner by INSEE's regional offices: the work was done by hand, in large notebooks. The digitisation and centralisation of the register began in 1973 (Ouvrir dans un nouvel ongletLang, 2018), in response to ever increasing demand from authorities, linked to a context in which many files were being digitised. Thus, since its creation, social security authorities have relied on the INSEE number for their organisation. However, the register is also very useful for citizens since it avoids errors, due to homonyms, for example, which could be very harmful to them (when their entitlements are calculated, for example, at the time they become eligible for payment of the old-age pension).

The National Directory for the Identification of Individuals (Répertoire national d'identification des personnes physiques – RNIPP) has, since a Decree of 1982, been the official name of this register, which serves as a reference for the identities and vital status of people in France.

It is a living register, changing every day through the recording of new events, as a true copy of those recorded by the municipal civil registries for people born in France (births, deaths, changes of surnames or forenames, sometimes of sex etc.) and by the services of the National Old-Age Insurance Fund (Caisse nationale d'assurance vieillesse – CNAV) for people born outside France. Its high level of quality is only possible through the mobilisation of teams in regional offices who ensure the completeness, reliability and availability of the register. What role does this register play in France today? How is it fed into and what mechanisms ensure its accuracy?

Since its inception, INSEE has been responsible for the management of the RNIPP. This register records, for any person born in France, regardless of nationality, all the events affecting their civil status as soon as the information appearing on the official registers has been transmitted to INSEE; it does not contain any other information relating to individuals (including their nationality or place of residence). At the time the first record is created in the register, registration, it unambiguously assigns a permanent identifier to an individual: this is the register registration number, the NIR, more commonly referred to as the "social security number" (box 1).

The first service provided by the RNIPP is therefore registration. Then, several events in people's lives will be reported by the municipalities to INSEE and recorded in the register. Primarily death when it occurs, but also changes of civil status (change of surname, forename or sex), so that the register remains an exact copy of the person's formal identity at all times. This identity is the one recorded in the civil registers of the 35,000 municipalities in France and the RNIPP must be an exact mirror image of it. It is the reference for the link between the identity traits (surname, forenames, sex and date and place of birth) and the NIR identifier. It thus makes it possible to offer an identification service consisting in confirming whether or not identity traits exist in a civil register, giving information on the status of the person, living or deceased, and providing their NIR.

In 2021, the RNIPP included more than 113 million individuals (box 2); it records around 2 million events per year.

The RNIPP variables, defined by Decree No 82-103 of 22 January 1982, number fewer than a dozen. In this respect, the RNIPP respects the stability characteristic of a register with referential status: structural, stable and reliable variables, of which there are therefore few, else it would be costly to ensure high quality, fresh data. Only the variables that are absolutely necessary for its function as a reference for people's identities are included.

The information recorded is thus the elements of people's identities as recorded in the civil status records held by the town hall: surname at birth and forenames, sex, date, place of birth and birth certificate number and, where applicable, date and place of death and death certificate number. Filiation and marital name are sometimes added when necessary for identification (in the case of homonyms, in particular) as well as previous identity traits (in the case of a change of surname, forename, sex etc.). It also includes the unique number generated by the register at the time of registration, the NIR. This number will remain attached to the person and will serve as a reference not only throughout their life, but also after their death. Indeed, the RNIPP does not delete any records, even after the death of the person concerned. There are cases in which the NIR changes do exist (in the case of a sex change, for example), but they remain very rare.

A register is not fixed and unchanging. It is a living system that changes every day, because the real world it represents changes. However, amendments to the RNIPP must always be based on official records. For people born in France, the main input source for the RNIPP comes from civil status records held by municipalities. For each event, civil registrars draw up records (birth certificates or death certificates, for example) and then transmit some of this information to INSEE to feed into the RNIPP. Civil registrars must respect deadlines for the transmission of information: one working day after birth certificates are drawn up, one week for death certificates and one month for other records.

In the event of a change, such as a name change or sex change, the RNIPP can only be amended once a new civil status record is drawn up that takes the change into account. These new records generally take the form of "margin statements" on the original civil status records. For example, if a person changes sex, the indication of the new sex will be added to the margin of their original birth certificate by the civil registrar of their municipality of birth, and this information will be sent to INSEE to update the RNIPP.

When drawing up the records, civil registrars follow instructions from the Ministry of Justice, brought together in the General Instruction on Civil Status (Instruction générale relative à l'état civil – IGREC), under the authority of the Public Prosecutor. For its part, INSEE gives instructions on how to transmit data from municipalities, but not in relation to the information itself. In particular, INSEE does not intervene regarding the acceptability of a forename.

This principle of compliance with civil status records has the advantage of making the information more reliable. However, paradoxically, this security requirement leads to a limitation: any event not recorded in a civil status record or not officially transmitted to INSEE is missing from the register. As a result, the death of a person outside France without transmission of the information to an organisation in France cannot be taken into account: this explains why the RNIPP can include people presumed to be alive when they are in fact deceased. So we find supercentenarians in the register! However, these people do not necessarily receive benefits from the French social security system. There is a control system established by the social security bodies to suspend payments when there is no evidence of recent life of the person.

However, the transmission of information by civil registrars is not limited to just the civil status data needed to update the RNIPP. INSEE takes advantage of the existence of these transfers of information to request other variables which, in this instance, have the status of statistical data rather than administrative data.

The collection of the data takes place within the framework of a statistical survey that is included in the programme of the National Council for Statistical Information (Conseil national pour l'information statistique – CNIS), is recognised as being of general interest and is mandatory in nature. The data collected enrich socio-demographic knowledge around important life events such as births, deaths, marriages, civil partnerships (and soon divorces). The database associated with the RNIPP, as well as with data collection for statistical purposes and the Permanent Demographic Sample (Échantillon démographique permanent – EDP), is called the Index Database of Natural Persons (Base des Répertoires de Personnes Physiques – BRPP).

This data includes, for example, the municipality of residence of the mother, which makes it possible to count births according to the place of residence of the mother (so-called "domiciled" births) and not just according to the place where she gave birth (so-called “registered” births). In a more traditional manner, information is also collected on employment status, nationality, marital status, etc. For certain events, more specific information is requested, such as the number of children the mother has already had at the time of each birth or the joint number of children between the partners at the time of entering into a marriage or concluding a civil partnership (PACS).

All of this information, both that relating to identity and that of statistical interest, is collected through forms called civil status declarations (box 3), of which there are ten. Most of them are used for both purposes: updating the RNIPP and collecting statistical variables, but some declarations are used for statistical purposes only. This is the case, for example, for declarations regarding the conclusion and dissolution of civil partnerships.

Civil status declarations exist in paper form, but information transmissions between municipalities and INSEE are largely digitised. In 2021, data on 99% of births, 94% of deaths and 81% of marriages was sent digitally. For that purpose, municipalities can use either an application made available free of charge by INSEE or a software offered by a private publisher. These software products on the market offer richer functions than the INSEE application, in particular they are not limited to the transmission of data to INSEE but include the entire civil status processing chain, including the part relating to drawing up the original record.

Giving life to the RNIPP also means maintaining regular data exchanges with municipalities, in particular to guarantee its completeness and quality. Despite the high level of digitisation, not everything can be automated. The day-to-day management of the proper functioning of this transmission system is thus ensured by 70 INSEE workers, within the "BRPP sites" in regional establishments, supported by a national hub in Nantes.

Indeed, the completeness of the information contained in the register, at least with regard to conformity with civil status records, is normally guaranteed by the regulatory obligation incumbent upon civil registrars to report all events to INSEE. In order to verify that there is no missing declaration, INSEE nevertheless organises completeness monitoring, with alerts when municipal transmissions are abnormally weak, when "holes" in the numbers of records or in the order are detected, or if assumed deaths not declared to the RNIPP are detected (for example, when information about a death is transmitted by social security bodies). In addition to these routine operations, more ad-hoc quality operations are organised, in particular an annual survey on the completeness of marriage declarations or others more focused on centenarians or individuals registered by mistake as duplicates.

The BRPP sites are also the contacts for the municipalities and provide them with advice and assistance, particularly on all subjects related to the digitisation of transmissions (conventional formalisation and technical assistance). They manage the flow of paper declarations to and from the input provider and carry out data recovery or corrections in the event of errors, as well as a little residual input. As a result, 96% of births are registered in less than 8 days and 97% of deaths are registered in less than 21 days.

The sites also process requests for the identification of persons for registration in the Single Electoral Register (Répertoire électoral unique – REU): this involves verifying the existence of these persons and recovering their official identity, when identification cannot be automated and requires a thorough analysis. Managers also analyse cases of presumed death, when information is sent by social security bodies.

People born outside of France must also be registered in the RNIPP when they come to live in France, even for a few months, to work, study or seek medical treatment. The employer needs a NIR to pay the employee's social security contributions and the NIR is also necessary for the employee to benefit from social rights, including health insurance. In order to be registered in the RNIPP and thus obtain a "social security number", people born outside of France must submit an application to a social security body (primary health insurance funds, family allowance funds, agricultural workers' mutual benefit funds, self-employed workers', funds, etc.). CNAV (National Old-Age Insurance Fund) will then process their application. Indeed, since 1987, INSEE has delegated responsibility for the registration of persons born outside of France to CNAV. CNAV will also continue to record all changes relating to these individuals.

CNAV thus manages the National Identification Management System (SNGI), a mirror repository of the RNIPP for the civil status part, which serves as a reference system for identification for all social security bodies for all persons born in France or elsewhere. It is in this system that people born outside of France are first registered and the NIR is first assigned. Both systems, the RNIPP and the SNGI, are synchronised each night with the new registrations or changes made during the day (figure 1). This allows the SNGI to recover all new registrations or changes concerning persons born in France and the RNIPP to do the same for persons born elsewhere. Thus the two registers are exhaustive and are identical with regard to identity traits, vital status and NIRs. The existence of the SNGI thus allows social security bodies to have their own system for verifying identities.

Figure 1 – Two registration routes for two complementary registers

*Here, the term "France" refers to metropolitan France, the French overseas departments, the communities of Saint-Pierre and Miquelon, Saint-Barthélémy, Saint-Martin, French Polynesia and Wallis and Futuna.

High quality work is regularly carried out jointly by INSEE and CNAV to check the consistency between the two registers. Indeed, despite this daily system of digital data exchanges, there can be various problems that result in discrepancies.

Three main categories of discrepancies have been identified:

The work carried out in 2021 on a sample of 16 million people makes it possible to estimate that the proportion of situations requiring correction to restore consistency between the two registers is 0.05%.

Despite all these actions to verify the quality of the register, both at INSEE and CNAV, people may occasionally be wrongly declared deceased. These cases are very rare but they can happen, particularly in the case of homonyms, very similar identity data within a family or mix-up of identities between the person who declares the death and the deceased, etc. Corrections are then made as quickly as possible.

The Decree of 1982 does not explicitly give the RNIPP purposes, but these are explained elsewhere by the National Committee on Information Technology and Civil Liberties, which defines it as "an instrument for verifying the civil status of persons born in France" (Ouvrir dans un nouvel ongletCNIL, 2009). It is also interesting to note that this Commission was originally created to control the uses of such a file (box 4). The RNIPP is a register that therefore has referential status. The data it includes is essential to unambiguously identify a person and whether they are living or deceased.

First, it allows certification of the civil status of a person, i.e. it allows an authorised body to verify whether a person who has claimed a given identity exists and is alive. It is thus not only used by social security bodies, via the SNGI, but also by the tax authorities, the Banque de France, the SIRENE register and by a growing group of other stakeholders.

However, the data contained in this register is very sensitive and is therefore protected. In order to have access to the information contained therein, in particular to be able to verify a civil status by querying the register, one must be authorised by a regulatory act. Since 2019, a specific Decree has listed all the categories of stakeholders and the processing purposes for which the use of the NIR or access to the RNIPP is authorised, in each sector of activity (social security, housing, labour, justice, finance, tax and customs, official statistics and censuses, and education), for example, "to have INSEE certify the civil statuses of natural persons holding bank accounts: the offices of the Directorate-General for Public Finance".

Any use of the NIR or RNIPP data that does not fall within the scope of the uses covered by this Decree is prohibited or must be covered by another legislative or regulatory text. INSEE systematically verifies that the requesting body and the processing undertaken are indeed referenced in the Decree. If this is not the case, INSEE refuses access to the data and explains to the requester the need to obtain authorisation, either by law or by an amendment to the Decree or another regulatory text.

The importance that the RNIPP has taken on in the French administrative organisation is due to the quality of the civil status information recorded there and the up-to-date nature of that information, as well as the interoperability of that register, in the IT sense of the term, with many other information systems. This is why the RNIPP plays an increasingly pivotal role in the French administrative system and, especially, for other registers.

Let us take the case of the REU, which has been in place since 2019 to manage electoral rolls (registration, removal, by municipality, as well as proxies) (Demotes‑Mainard, 2019). During the organisation of elections, the electoral rolls are taken from this register. When a person registers to vote, their civil status is verified in advance using the RNIPP.

This first makes it possible to verify that the person exists and has not died, while also making it possible to recover their complete and official civil status. This civil status is then used as a reference in the REU (and is registered on the voter's card).

The establishment of the REU in 2019 also gave many voters the opportunity to discover their official civil status as it exists in the RNIPP, because it was shown on their voter card for the first time. Some people then sometimes noticed errors, relating to their surname or forename. This could stem from input errors or changes not transmitted to INSEE by the municipality of birth.

This wide-ranging information on voters thus allowed a major quality operation to be conducted on the RNIPP. Out of the 85 million living people in the register, there were 45,200 changes in civil status made by INSEE for people born in France (68% concerning forenames and 30% concerning surnames) and there were 58,000 changes for people born outside of France (thus made by the CNAV). This gives a total of 103,200 changes (0.1% of the register). This was a great deal of work for the INSEE and CNAV teams, which was carried out in a few months.

The SIRENE business register identification system also uses the RNIPP to verify the identity of individual entrepreneurs at the time of their registration. This again makes it possible to be certain of the identity of the creator of the company and that they are still alive. If the company subsequently has problems with its customers or suppliers, this will enable the latter to initiate legal proceedings without unpleasant surprises.

Initially confined to the social sphere, the RNIPP plays an increasingly structural role in the French administrative system. The number of "customers" has been growing steadily, with an acceleration in recent years where between 20 and 30 million identification requests are recorded each year (excluding FranceConnect). More recently, the arrival of FranceConnect has further increased the use of this register.

Created in 2018 by the DINUM (Direction interministérielle du numérique et du système d'information et de communication de l'État – Interministerial Directorate for Digital Affairs and the State Information and Communication System), FranceConnect is a remote service that makes it possible to secure and simplify the connection to over 1,000 online services in 2022. It gives each user the ability to use a digital identity (username and password) linked to an operator to access the services of other operators. Thus, as an example, a user can use their Améli credentials to connect with the tax authority. It is no longer necessary to remember a plethora of usernames and passwords.

Before authorising access to the desired service, FranceConnect verifies the identity of the user by comparing it with that in the RNIPP. Access is only permitted if the two identities match. The availability of the RNIPP consultation application is thus crucial to ensuring the proper functioning of this ecosystem. This is especially true given that the number of consultations of the RNIPP via FranceConnect has steadily increased, from 8 million users in 2019 to 37 million in 2022. Requirements relating to robustness, availability and load-bearing capacity are therefore of prime concern for INSEE, in order to ensure the expected level of service.

In the event that an error is identified by a citizen in relation to data concerning himself, it is essential that it can be corrected quickly so that the damage is as minimal as possible. This is why, in 2019, INSEE and the DILA (Direction de l'Information légale et administrative – Directorate of Legal and Administrative Information) established an online procedure for citizens to request the correction of their civil status by sending a copy of their birth certificate.

This service is accessible only for people born in France, on the official French government department website. While waiting for a similar service to be developed, people born outside France may contact their social security organisation.

Some people do not have Internet access; however, it remains possible for them to request a correction of their civil status by mail, addressed to INSEE for people born in France, or to their social security body for people born outside France.

As can be seen, the RNIPP has two strong characteristics.

Firstly, the personal consequences of mismanagement of this register are potentially serious. They can lead to difficulties in benefiting from social security entitlements, such as receiving an old-age pension, or in accessing services (digital or analogue) requiring identification, or worse: being wrongly declared deceased.

Secondly, its information system interacts with many others (CNAV, FranceConnect, publishing software of municipalities, etc.) and this interoperability must remain operational at all times.

In this context, the proper functioning of the management of this register imposes stringent requirements of multiple kinds:

Meeting these requirements involves carrying out numerous actions, in relation to both the content of the register and its information system. A large-scale campaign to integrate all French people born outside France into the RNIPP, in connection with the CNAV and the Central Civil Registry Service of the Ministry of Europe and Foreign Affairs (and not only those who make themselves known to benefit from social security entitlements), was conducted in 2022, with the aim of facilitating the formalities they must complete if they return to France or the formalities they must complete online to access remote French services. Similarly, actions to improve the identification of people born outside France have been launched, in order to facilitate their access to FranceConnect.

The requirements for maintaining interoperability arise in a context in which interactions with the information systems of other government departments involve various techniques. First of all, web services, with CNAV as the main partner for feeding into the register, but also with the major operators of administrative procedures (FranceConnect, SIRENE and the one-stop shop for company registration). Data exchanges with the municipalities via private publishing softwares also pass through APIs. Finally, the file deposit-retrieval technique is widely used for identification services, for example with tax authorities or banking or insurance organisations (figure 2).

Figure 2 – The RNIPP, identification at the heart of both the administrative and the statistical fields

All of the data exchanges must respect the standards. The standards are made public and published on INSEE's website (INSEE, 2021). For exchanges with the municipalities, these standards primarily focus on the format of the files. They are also expressed in the form of data entry instructions, in particular concerning permitted diacritical marks, ligatures, the use of dashes or apostrophes or even the abbreviations of place names. Thus, only the Latin alphabet and diacritical marks recognised in the French language are permitted.

In the same way, exchanges with clients of the identity certification service must respect the file formats prescribed by INSEE, as well as the transmission methods and data security.

The availability conditions of the information system are also monitored regularly with regard to the workload associated with requests. In 2021, the RNIPP was available for FranceConnect 99.5% of the time. However, the scope of this service continues to grow, for example with the recent addition of the Family Allowance Funds, which naturally generates many new users. These changes in the connection workload may lead to regular adaptations of the IT system.

Once a person is registered in the RNIPP, they stay there indefinitely. Immigrants may return to their country of birth, but they remain registered in the RNIPP indefinitely. If they return to live in France one day, they will have no new formalities to complete and will be able to use the NIR given to them "for life". If they die outside France, the information will likely not be known and they will be kept alive in the register. This explains why the RNIPP is unable to provide figures for the population living in France and is therefore not a population register (Ouvrir dans un nouvel ongletPoulain and Herm, 2013). Indeed, a person's address is not one of the variables recorded in the register, which means that it is not possible to determine the number of people present in the RNIPP who do not live in France. Thus, the RNIPP includes 85 million people presumed to be alive while, according to the French population census, the population living in France is estimated to be 68 million as at 1 January 2022.

However, the RNIPP does allow INSEE to produce demographic statistics. Each year, the demographic balance of France and its territories is based on these data (Papon, 2022). This is how major demographic indicators are estimated, such as the number of births and deaths in France, the number of children per woman, life expectancy at birth, etc.

The register also played a major role in France during the Covid-19 epidemic. INSEE and the French National Health Agency (Santé publique France) worked together to set up mortality surveillance very quickly in March 2020. A section of the INSEE website dedicated to monitoring all-cause mortality was created and updated weekly at the beginning of the epidemic and then with variable frequencies depending on the severity of the crisis (INSEE, 2022).

Aside from this ad-hoc use linked to the Covid-19 crisis, the RNIPP also plays a role in the production chain for cause of death statistics. These causes, identified by the doctor who signs the death certificate, are processed and analysed by INSERM within a framework that respects medical confidentiality, but the completeness check is carried out using the data in the register.

In addition, the statistical variables collated in the civil status declarations on profession, nationality, marital status etc. are the subject of specific publications and are distributed in the form of detailed tables and detail files on the INSEE website.

Some data from the RNIPP are also integrated into a large demographic panel, the EDP. This socio-demographic panel, which brings together several data sources, was set up in France to study fertility, mortality, family trajectories, geographical migrations within the national territory, social, occupational and residential mobility, careers and standards of living, as well as the possible interactions between these different aspects.

Finally, the RNIPP is also used for sampling and to enable the implementation of surveys on specific topics. This can be for monitoring a specific category of the population, centenarians for example, or for the needs of epidemiological studies.

The RNIPP and the transmissions of statistical information adapt to changes in society. In the case of the RNIPP, these are mainly changes caused by legislative changes; for the statistical field, it is more generally a question of better reflecting the realities of society. Thus, the Bioethics Law of 2 August 2021 established the "PMA pour toutes" (MAR for All Women) (medically assisted reproduction for female couples) which led to the change of the birth declaration and its associated declarations (still birth and birth declaration judgment) to allow the registration of two female parents, as well as the change of the declaration of a margin statement for recognition of a second mother.

Changes in the area of conjugal relations have also been significant in recent years. The introduction of civil partnerships led to the creation of two new statistical declarations (conclusion and dissolution of civil partnerships). Similarly, the introduction of divorces by mutual consent before notaries (or divorces outside the judicial system) in addition to divorces by judicial procedure has led to a review of information collection channels. While information on divorces by judgment is traditionally transmitted by judicial institutions, it has been necessary to devise a new mechanism for divorces before notaries. Thus from 2023, INSEE will collect the statements of divorce entered into the margins of marriage certificates in order to be able to establish statistics on the evolution of divorces in France, because this data is currently incomplete.

In a completely different field, that of epidemiological studies, the Covid-19 health crisis has also highlighted the important need for statistical information on deaths at sub-municipal level. Until now, the location of the deceased's home has been limited to municipal level, which made analyses by neighbourhood difficult, which then required the use of additional sources of information. As of 2023, the address of the deceased's home will be included in the death declaration, which will allow data to be used for operations at sub-municipal level.

A major redesign of the declarations will thus be operational in 2023. This redesign was carried out following broad consultation with the main users of the data from the civil status declarations (Ministry of Justice, INSERM, INED, DREES, High Council for the Family, Children and Age, National Union of Family Associations, etc.) and was awarded the public interest and statistical quality labels. In addition to the changes already mentioned, there is also an update to the collection of data on profession, marital status and places of birth or death. This redesign will also be an opportunity to modernise the process of matching causes of death and declarations of death through a more efficient use of the non-identifying number generated by the IT application for the digitalised transmission of the death certificate. Also in the area of healthcare, the RNIPP will soon contribute to the French national health data system.