Two systems one vision
A new European Commission report identifies and explores 6 synergies between the Once-Only Technical System and EU Digital Identity Wallets that can reduce implementation costs and improve the user experience for citizens.
Exploiting synergies between the two initiatives
These aren't competing systems, they're complementary tools that each excel at different things.
Enables public authorities across Europe to securely identify and map the official documents required to complete a cross-border administrative procedure, request and exchange them, with the citizen’s permission, so the same information only needs to be provided once.
- Official record verification
- Authentic sources
- Cross-border exchange
ExampleA citizen relocating from Spain to Germany for work no longer needs to collect or translate their diploma. With the citizen’s consent, German authorities can directly request the official verified document from Spain through OOTS.
Provides a secure digital wallet that stores our official credentials, such as identity documents, and official attestations like driving licences, or diplomas and enables users to share only the specific information required for a given service. It provides a secure, privacy-enhancing, and accessible means of digital identification to every EU citizen and resident.
- Personal credential storage
- Online & offline identity
- Selective disclosure
ExampleWhen purchasing an age restricted item online, citizens can use their EUDI Wallet to instantly prove their identity and age online without disclosing any additional personal details that can be used to identify or profile them.
The result
- Cost savings
- Better user experience
- Faster time-to-market
Six ways the systems can work together
Synergy 1Better UXCitizens can identify themselves to OOTS using their EUDI Wallets
Citizens would be able to use their EUDI Wallet to identify themselves to OOTS procedure portals, for example when applying for university financing.
Synergy 2Better UXIssue documents to EUDI Wallets direct from the OOTS preview area
The Once-Only Technical System would issue evidence and procedure outputs to EUDI Wallets in compatible formats. Users can identify and retrieve cross-border evidence through OOTS, then store and present it via their EUDI Wallet.
Synergy 3Better UXCitizens and businesses can combine data from EUDI and OOTS.
Member State procedure portals would be able to let citizens submit required documents through their EU Digital Identity Wallet if they have one or alternatively request the automatic retrieval of the requested documents from another EU country via Once-Only.
Synergy 4Cost savingsIssuers of qualified EUDI digital documents could use OOTS to verify attributes before document issuance
Enables Qualified Trust Service Providers (QTSPs) i.e. as issuers of digital documents to EUDI Wallets, to identify the relevant authentic source and subsequently request the verification of attributes before issuing the attestation.
Synergy 5Cost savingsCitizens and businesses can use OOTS to find digital documents for their EUDI Wallets.
The Once-Only Technical System’s Common Services could function as a directory of public bodies that can issue attestations to EUDI Wallets.
Synergy 6Cost savingsEUDI Wallets use OOTS to store data and technical info on compatible digital documents
The OOTS Semantic Repository could store information on rules and data formats for EUDI compatible digital documents, serving as a general overview.
EUDI service providers could consult it when needed.
Want to learn more ?
Download the full report to dive deeper into the OOTS-EUDI synergies, including the legal and technical implications of each synergy.
Who wrote the report?
The report was developed by a Commission group of experts formed in 2022, bringing together experts from:
- The Single Digital Gateway Coordination Group
- The European Digital Identity Cooperation Group (EDICG)
- With the support of DG GROW, DG CNECT, and DIGIT.
The end result is a comprehensive analysis of how OOTS and EUDI Wallets can evolve together to build an integrated, efficient, and user-centric digital Europe.
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Continued collaboration between OOTS and EUDI enhances interoperability, security, and efficiency.
Kirsi Mikkonen Chief Specialist
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The benefits of the synergies are clear. They are ready to be implemented by the Member States.
Gertjan Bouwers National & European eID EUDI & SDG Expert
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Both EUDI and OOTS support Europe-wide interoperability and both systems stand to greatly benefit from aligning their functional principles.
Georg NesslingerHead of Division E-Government for Businesses
Project timeline
The Single Digital Gateway Regulation is adopted (Regulation (EU) 2018/1724)
Implementing Regulation (EU) 2022/1463(opens in a new tab) is adopted, laying down the operational and technical specifications for OOTS
Commission establishes the group of experts
Interim “Synergies between the Once-Only Technical System and the EU Digital Identity Wallet” report published(opens in a new tab)
EU Digital Identity Regulation is adopted (Regulation (EU) 910/2014 following amending Regulation (EU) 2024/1183)(opens in a new tab))
Final “Synergies between the Once-Only Technical System and the EU Digital Identity Wallet” report published
The synergies explained
Watch the video below to learn more about each of the synergies, including how they work and how each system interacts.
Technical resources for implementers
Are you interested in implementing OOTS or EUDI Wallets, or even both systems? These technical resources can help you on your journey.
Technical Design Documents (OOTS)
Explore the Once-Only Technical System's technical and operational specifications as well as detailed, non-binding technical design documents created jointly by the Commission and Member States.
EUDI GitHub
Here you can find tools to help you join the EUDI ecosystem, including open-source code libraries, modular components, and a working reference application based on the Architecture Reference Framework (ARF).