1 Introduction

The ‘once-only’ principle (OOP) is a crucial element in the delivery of the user-friendly digital public services and modernisation of public administration. Providing the same data over and over again is troublesome and time-consuming both for citizens and businesses. It is also not reasonable since most of the data is already stored in authoritative sources. The key is to enable public administration to retrieve it in an efficient and safe way.

EU-wide implementation of the OOP is one of the priorities of the European Commission, which is reflected in the strategic documents. The principle appeared for the first time in 2009, when the Member States committed themselves to, among others, jointly investigate how public administrations can reduce the frequency with which citizens and businesses have to resubmit information, by signing the Malmö Ministerial Declaration on eGovernment [38]. Reduction of administrative burdens by applying the principle of "once-only" registration of data for citizens was one of the actions of the eGovernment Action Plan 2011 – 2015 [25]. Furthermore, the principle has been highlighted in the European Council Conclusions in October 2013 [29] by stating that “efforts should be made to apply the principle that information is collected from citizens only once, in due respect of data protection rules”. Another the OOP milestone was signing the 'eGovernement Declaration' in Tallinn on 6 October 2017 [28], in which 32 countries of the European Union and the European Free Trade Area made a political commitment to implement the principle for key public services. Furthermore, in the EU eGovernment Action Plan 2016–2020 [26] the OOP is listed among other principles for effective eGovernment such as digital by default, inclusiveness and accessibility, openness and transparency, cross-border by default, interoperability by default, trustworthiness and security. According to the Plan, “public administrations should ensure that citizens and businesses supply the same information only once to a public administration. Public administration offices take action if permitted to internally re-use this data, in due respect of data protection rules, so that no additional burden falls on citizens and businesses”. Additionally, a recommendation to “as far as possible under the legislation in force, ask users of European public services once-only and relevant-only information” is provided in the new European Interoperability Framework [27] within the user-centricity principle for establishing interoperable European public services. Finally, the Single Digital Gateway Regulation [30] provided legal basis for the cross-border application of the OOP, that should result in citizens and businesses not having to supply the same data to public authorities more than once, the possibility to use those data at the request of the user to complete cross-border online procedures involving cross-border users. According to the Regulation, by December 2022 a dedicated technical system will connect the 21 online procedures, key for citizens and businesses, established in each Member State with the data sources across Europe.

Even there is no one concrete definition of the OOP, based on the EU level documents mentioned above, the following elements of the OOP can be identified:

  1. 1.

    collecting only necessary information,

  2. 2.

    exchanging data so the citizen or entrepreneur is never asked again,

  3. 3.

    respecting data protection rules when re-using data.

2 National Approaches Towards Implementing the OOP

Although the OOP is relatively new in the actions of the European Commission, it seems that the Member States realized its benefits a long time ago. In many countries, this has been a natural reaction on isolation of databases. The existence of numerous registries not linked with each other caused low quality of the data, redundancy of data collected, work duplication of administrative workers, and dissatisfaction of the citizens and businesses due to the growing red tape. Although most countries face similar challenges, understanding and the way of application of the OOP may vary. National differences such as different administrative structures, IT systems, database models affect the deployment of the EU-wide OOP.

The table presented in Appendix provides an overview of national OOP implementations of EU Member States and European Economic Area countries (Norway, Island, Lichtenstein). The table was developed based on the available online sources (Digital Government Factsheets of 2019 published by the European Commission’s National Interoperability Framework Observatory, collection of Joinup cases, national sources) as well as information gathered from the TOOP partners and representatives of Member States. The table includes information on the legal basis of the OOP, national programs/actions supporting the OOP and the solutions enabling realization of the principle. The information in the table, especially related to the solutions enabling the OOP, refers to the business data exchange (among other data). Therefore, the OOP applications in sectors such as health, justice, social security etc., which are often supported by a dedicated infrastructure are intentionally not presented (Fig. 1).

Fig. 1.
figure 1

Legislation, strategies and infrastructure for OOP in the EU Member States and EEA countries

Legislation can be an important driver for the application of the principle. Most of the countries (22 out of 30) have national legislation for OOP in place. Not all regulations directly prohibit requesting data more than once. Legislation obliging authorities to obtain and reuse data stored in public administration databases as well as introduction of meta/base registries are also treated as OOP enabling regulation (e.g. case of Slovakia, Norway, Finland, Croatia, Czech Republic). Base registries provide authentic sources of data for public administrations, and therefore, are the key to making the OOP a reality [23]. In some EU countries, law does not only prevent the collection of data more than once but also ensures that data are stored only in one place. For example, the Estonian law prohibits the creation of separate databases for the collection of the same data [46]. Public institutions exchange information between each via a system called X-Road. Information, stored in decentralized registers can be securely accessed through a data exchange layer. Additionally, in the case of Estonia, the legislation is used to force the use of the X-road solution, which is a recommended good practice [23], facilitating the broad uptake. In the Netherlands, the common rules for the base registries [22] do not permit to collect data that is already stored in any of the registers. Sharing and exchange of data are enabled by four system services Digikoppeling, Digilevering, Digimelding and the Stelselcatalogus [18]. Duplication of data held in the central business registries (the Business Registry and the Private Entrepreneur Registry) is also not allowed in Hungary. Public administration bodies are obliged to retrieve data from the registries via secure data exchange. The legal obligation for OOP does not exist in Denmark, Greece, Iceland and Sweden. Lack of the OOP legal basis in Sweden may be justified by the “Swedish tradition” that common infrastructure is governed through guidelines and recommendations. Therefore, the OOP is underlined in the national digitization plans but not dedicated legislation. No data was found for Cyprus, Latvia, Lichtenstein and Malta. It must be however remembered that the Single Digital Gateway Regulation, which mandates the use of the principle from 12 December 2023, became immediately enforceable as law in all Member States when it entered into force in 2018. In this way, each EU country has legal basis to enable at least key OOP based digital services.

The OOP is often seen as a part of a global plan of public services modernization and cutting red-tape and therefore is part of national programs and strategies related to digital government. 18 (out of 30 countries have highlighted the principle in the documents such as digitalisation strategies, interoperability strategies, or programs dedicated to reducing administrative burden. For example, The Dites-le-nous une fois (Tell us once) is part of a global plan to modernise public services in France and is one of a range of actions being taken to digitalise processes and improve collaboration between ministries and public services [35]. In Luxembourg, the OOP is one of the five eGovernment principles, approved within “Digital Luxembourg”. OOP is the core goal of the “Mapping Tomorrow”, which is a strategic plan for the public administration for 2019–2021 in Malta, aiming at internal sharing and re-use of data and information that has been previously provided by a citizen or organisation. 5 countries have not highlighted the OOP in any strategic documents. No data was collected from 7 countries.

The infrastructure enabling the OOP is in place in 22 (out of 30) countries. The solutions are at various maturity levels and cover different scope of information.

The MAGDA platform (Maximum Data Sharing between Agencies) of Belgium is connected with base registries at the federal level through the relevant service integrators. In France, where the OOP principle was implemented along with a wide range of base registry initiatives, public administrations can access this information through APIs (Apientreprisesl) that provide information from different base registries. In Hungary, the Central Governmental Service Bus, the technical interoperability platform, which is online since 1 January 2018, enables automatic information exchange from 27 base registers indicated in the e-Administration Act. Others can also connect to provide their services over the central data exchange platform voluntarily. Furthermore, the Public Connectivity System [51], one of the Italian OOP solutions, is a network that connects Italy's government agencies, allowing them to share and exchange data from six base registries based on Domain Gateways (Data Providers and Consumers). Another OOP solution in Italy is the National Digital Data Platform (PDND). The X-Road system, which is the backbone of the OOP in Estonia, enables multiple databases to communicate. Apart from Estonia, the solution is already implemented in Finland and Iceland. Not all Member States realize the OOP by the deployment of the data exchange infrastructure. In Denmark for example, Data Distribution Platform, an authoritative data source infrastructure makes basic data from several authorities accessible in the same place. In this way, the Platform ensures that authorities are provided with easy and safe access to basic data in one collective system.

The OOP solutions are often interconnected with the Points of Single Contacts (PSC) for businesses operated in each Member States, following the implementation of the Directive 2006/123/EC on services in the internal market [49]. The business portals facilitate access to information and the completion of administrative procedures online. Luxembourg has implemented the OOP by making it a component of the Guichet.lu whilst in Norway, the exchange of information from business registries at the Altinn system (PSC) is possible thanks to the Central Coordinating Register for Legal Entities. In Sweden, the Composite Service of Basic Information on Companies, which supports the exchange of business-related data, collects and forwards replies from the PSC - verksamt.se portal, (as well as municipalities, government authorities) to data sources (Swedish Tax Agency, Statistics Sweden, Swedish Companies Registration Office). In Estonia the X-Road system is the basis for the core-functionality of eesti.ee among other portals.

No central infrastructure supporting the OOP is currently available in Germany, Greece, Poland and Romania, although for selected services the automatic data exchange is gradually being enabled (e.g. business registration service in Poland). No information was found for 3 countries.

Looking from the European perspective of the once-only, different maturity levels as well as fragmentation of the OOP applications significantly hamper extending the principle to the cross-border level. Still, in some Member States, the OOP is not applied horizontally but has a limited – service-oriented character. Exchange of data in selected processes or a single database is an indisputable added value for a business but does not realize the OOP in general. This quite low level in the OOP advancement is reported in countries such as Poland and Greece, although a more holistic approach is envisaged in national plans and strategies.

3 Benefits of the OOP

The once-only principle puts the public services user in the centre. Public administration eliminates burdens in access to public services by reorganizing internal processes and enabling cooperation between public bodies. Implementation of the OOP is not only about exploiting the advantages of new technologies but overcoming organizational as well as legal challenges. Thanks to this effort, handling administrative matters becomes more efficient and friendly. The principle refers both to retrieving documents required as attachments to the form as well as filling the form with necessary information. The time required to prepare a form to be submitted to the public office is limited to the minimum as only data and documents that the administration is unable to obtain on its own are requested. Keeping data up-to-date, which is citizens and business responsibility imposed by law, also becomes less cumbersome. In the case of dispersed and not interconnected registries, there is a risk that citizens or businesses might lose control over data submitted in various databases. The interconnection of databases enables swift notification of respective sources in case of change submitted to the one place. Furthermore, the OOP has a great potential of minimizing administrative burden for businesses in meeting the reporting obligations. The businesses during its operation need to submit numerous reports related to taxes, employment, working conditions, fixed assets, financial information and many others. The research conducted in 2019 Poland reviled [32] that an average Polish entrepreneur in a medium-size company needs to submit 208 reports. The authors of the report say the data submitted to the different bodies (up to 14) are often duplicated or unnecessary. This area has been the case of OOP application in some countries. The Register of the Reporting Obligations of Enterprises in Norway is responsible for a constant overview of the reporting obligations of enterprises to central authorities and finding ways to coordinate and simplify these obligations. In the Netherlands, Standard Business Reporting was introduced. It provides governments and businesses with a secure method for the exchange of business information between organisations in a reporting chain [18].

The OOP is expected to bring savings to businesses in terms of time devoted to multiple submissions of the same data and in turn complying with administrative requirements. According to an OECD Survey [35], 3 companies out of 4 consider that reducing repeat requests for information should be a government priority. As an example, it is estimated that data related to revenues and the workforce is, on average, requested from companies by public services between 10 and 15 times, which generates the cost between 3% and 5% of GDP a year.

A breach in the OOP has an impact on creating an administrative burden for citizens but public administrations are negatively affected as well. It fosters building administrative silos and lowers the efficiency of public processes. Ineffective processes related to data management generates extra workload. Additionally, duplication of the same actions by different bodies is costly for governments as extra effort needs to be put on ensuring data quality and reliability.

Investing in solutions related to enabling the OOP pays off. One of the examples is the Basic Data Programme in Denmark which introduced the OOP for many data collected in 10 electronic registries. According to estimations, it is expected to have annual revenues of around € 100 million, since the number of transactions between citizens/businesses is limited and the burden of reporting information is reduced [31]. Another example is the estimation on the application of the OOP, which has been carried out based on the Register of non-residents (RNI) in the Netherlands. RNI allows for data sharing among Ministries and National Agencies, which generates time savings related to the reduced number of transactions related to collecting and managing data. In line with the OOP principle, users registered in the RNI have to communicate their data only once to public authorities. As a result, a 50% decrease in potential transactions between users and public authorities was reported. According to estimation, the RNI generated benefits of €112 million [31].

Bringing the principle to the European level is expected to bring further benefits. For many years, the European Commission is devoted to making the citizens and business life easier by enabling seamless digital public services. Application of the OOP further improves their quality and contributes to the creation of the real Digital Single Market. Furthermore, it is expected that extending the OOP to the EU level could result in significant savings, estimated for as much as €5 billion per year [24]. However, the final benefits, as well as savings, will depend on the scale of the OOP application – the more data from various registries is exchanged the higher savings can be expected. Currently, information about citizens and businesses is reused only in 48% of cases.

4 Implementing the OOP in the TOOP Project

On 1 January 2017, the Once-Only Principle Project (TOOP) was launched with the aim to investigate and demonstrate the practical operation of the “once-only principle” in the field of cross-border public services to businesses in the EU Member States.

The substance of the OOP across borders is shown in the diagram below. It shows the case where a user from country B intends to execute a public e-service in country A. To do so, he starts the service in the service portal of country A (Data Consumer). The one-off principle is fulfilled in such a way that the service portal in country A retrieves the data of the user from country B directly from the system in country B (Data Provider). The aim of the TOOP project was to create an architecture that would enable data exchange as shown in the figure. The architecture developed in the project is federative as it is dispersed and does not create a single central system but enables data exchange between existing public administration systems in different EU Member States and associated countries (Fig. 2).

Fig. 2.
figure 2

The TOOP architecture concept

The technical solution developed in the TOOP project has been tested in three pilot areas: general business mobility, e-procurement and maritime pilot.

4.1 General Business Mobility

The TOOP architecture is used to facilitate the provision of cross-border services related to obtaining licences and permits for companies planning to do business in a Member State associated country other than their home country. The developed IT architecture enables business data to be automatically transferred from one system of a country to another, without the need for the entrepreneur to submit it again. This not only saves costs and time, but also improves data quality and consistency.

An exemplary cross-border implementation of e-services looks based on the TOOP project architecture is following:

  1. 1.

    an entrepreneur from Poland visits the eGovernment portal in Germany in order to obtain the permission necessary to provide the service in Germany;

  2. 2.

    the eGovernment portal in Germany authenticates the Polish entrepreneur through the eIDAS solutionFootnote 1;

  3. 3.

    the Polish entrepreneur begins the process to obtain a permit in Germany. The eGovernment Portal in Germany verifies through the TOOP architecture what data is already stored in the Polish register. In case the data is available, it notifies the Polish entrepreneur and asks him/her for consent to download the data directly from the Polish register;

  4. 4.

    if the consent is given, the data is retrieved directly from the Polish register and the Polish entrepreneur completes only data, which are not available but necessary to obtain permission in Germany.

4.2 E-procurement

In the area of public procurement, TOOP solutions will facilitate the implementation of procedures related to the contractors' compliance with the requirements for participation in the tender procedure. The technical solution created in the project enables automatic completion of the European Single Procurement Document (ESPD)Footnote 2, which is one of the documents required to be presented by the contractor participating in the tender procedure. Thanks to this, the process of verification of documents submitted by contractors participating in public procurement procedures is faster and easier. The TOOP solution can also support further stages of the procurement process. In the award phase, the contracting authority will retrieve the evidences, which have been declared in the ESPD by the winner of a tender procedure, directly from the competent authority of the country in which the tenderer is registered. To make this automatic data exchange possible the contractor needs to give an appropriate consent so the data can be accessed by the contracting party. The process can be repeated multiple times after awarding a contract.

4.3 Maritime Pilot

The application of the OOP in maritime transport is aimed at eliminating the need to provide ship and crew certificates, which are currently issued and kept in paper form by national maritime authorities. Ship and crew certificates are issued by various organisations such as the Maritime Administration and the Recognised Organisation. According to International Maritime Organisation (IMO) Conventions, these certificates should be "available in its original form on board the ship on which the holder is serving". The shipowner and, in practice, the ship master acts as an intermediary between the issuer of the certificates and the entity that requires them to be presented, i.e. the Port State Control Officers (PSCOs). Thus, an entrepreneur - the shipowner in this case, is burdened with providing information which is already in the possession of the public administration. The purpose of implementing the OOP is to enable PSCOs to access directly the databases of certificate issuers. This would result in automating a largely manual and paper-based procedure, which is used now.

5 Summary

The article presents the definition of the OOP and discusses the most important EU initiatives to make it a reality in Europe. The analysis carried out indicates that in most EU countries, the principle is both embedded in national legislation and indicated in national eGovernment strategies. However, having legislation is not equivalent to the practical functioning of the OOP. Some countries still have only solutions limited to selected group of services or registers and the priority is given to the national level applications. Such an approach already brings tangible benefits of reducing bureaucracy, but much higher savings can be generated at cross-border level and broad application of the OOP. This is the aim of the TOOP project, which has created a generic IT architecture, tested by a number of eGovernment systems in 19 European countries. The solutions developed in the TOOP project will be used in the implementation of the Single Digital Gateway. Its launch in 2023 will be a significant landmark for the OOP in the EU and the EEA countries and the next milestone in the development of seamless cross-border digital services.