Discover everything you need to know about the Once-Only Technical System.
Moving forward, when completing administrative procedures abroad, citizens and
businesses no longer need to search for their official documents.
With the Once-Only Technical System (OOTS), public authorities can exchange
verified data directly at citizens' request, reducing paperwork and making
cross-border admin faster, cheaper and more reliable.
Save time and money on cross-border services. Work more efficiently with trustworthy, real-time data. Gains mobility, competitiveness, and cohesion across Member States.
data exchange
The Once-Only Technical System:
Simplifying cross-border
data exchange
The EU infrastructure enabling secure, seamless cross-border data exchange between public authorities.
Freedom to move, work, and study without the paperwork
The Once-Only Technical System can benefit everyone in the Single Market
Citizens & Businesses
Public Administrations
The European Economy
Many procedures, one effortless experience
The numbers behind the Once-Only Technical System.
Unlock tomorrow with Once-Only today
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Implementation tracker
Take a look at how the European Union has been implementing the OOTS with the Acceleratormeter.
Learn more
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Join our events
Read how Member States and Authorities have been implementing OOTS, and get involved through our Projectathons and future local events.
Learn more
Latest news
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Once-Only Evidences Going-Live! EU Countries Publish Education Evidences (Q2 2026) (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/982090011/illu-news-oots-06-08-2026-bis.jpg
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Once-Only Evidences Going-Live! EU Countries Publish Population Evidences (Q2 2026) (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/982089979/illu-news-oots-06-08-2026.jpg
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EU Institutions release Joint Declaration on Legislative Priorities 2026 – One Europe, One Market Roadmap (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/973932476/illu-news-oots-03-06-2026-02.jpg
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Commission Publishes Patches for OOTS TDDs (2.0.1, 1.2.5, 1.2.5X) (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/978682129/illu-news-oots-16-07-2026.jpg
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The Committee of the Regions urges user-friendly European Business Wallets for SMEs and entrepreneurs in line with OOTS (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/978681863/illu-news-oots-13-07-2026.jpg
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Once-Only Services Going-Live! Working as qualified social care worker in Austria (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/973932855/illu-news-oots-08-07-2026.png
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Austria and Finland confirm ‘Once-Only’ Live Transactions in Health and Professional Qualifications (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/973932457/illu-news-oots-03-06-2026.jpg
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Commission updates Once-Only Technical System Acceleratormeter, June 2026 (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/973932288/illu-news-oots-01-07-2026.jpg
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State of the Digital Decade 2026 calls for Prioritisation of Once-Only Technical System (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/973931523/illu-news-oots-22-06-2026.jpg
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EU Frontrunners in Business Procedures Discuss the Road to ‘EU Inc.’ with ‘Once-Only’ (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/971800999/illu-news-oots-08-06-2026.jpg
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“Europe Goes Once-Only – Malta edition” accelerates the onboarding of competent authorities (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/973930901/illu-news-oots-16-06-2026.jpg
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Once-Only Services Going-Live! Applying for Tertiary Study Financing in Austria (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/971801662/illu-news-oots-11-06-2026.png
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2026 Spring semester package steering EU economies to increased competitiveness (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/971800741/illu-news-oots-08-06-2026.jpg
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Third SDG Coordinators Café: national coordinators take stock of OOTS implementation (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/967116425/illu-news-oots-26-05-2026.jpg
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Once-Only Services Going-Live! Exchanging professional qualifications in health and social care in Finland (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/967116642/illu-news-oots-28-05-2026.jpg
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The benefits of ‘Once-Only’ for Competent Authorities (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/964168082/illu-news-oots-05-05-2026.jpg
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SDG Coordinators Café: OOTS Business Procedures mean EU Inc will achieve One European Single Market (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/967115002/illu-news-oots-12-05-2026.jpg
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Once-Only Evidences Going-Live! EU Countries Publish Education Evidences (Q1 2026) (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/964167606/illu-news-oots-30-04-2026.jpg
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European Institutions agree Roadmap to achieve “One Europe, one Market” by end of 2027 (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/964167145/illu-news-oots-27-04-2026.jpg
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Once-Only Evidences Going-Live! EU Countries Publish Population Evidences (Q1 2026) (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/964166065/illu-news-oots-23-04-2026.jpg
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Watch Once-Only Studio interview with Maltese SDG team (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/962560103/illu-news-oots-15-04-2026.jpg
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2025 saw EU step up efforts for a simpler and more competitive Single Market (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/956170244/illu-news-oots-13-03-2026.jpg
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Once-Only Services going-live! Applying for a tertiary education study financing in Finland (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/920060755/illu-news-oots-25-09-2025.jpg
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Workshop brings the Western Balkans closer to Europe’s Single Digital Gateway (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/956171065/illu-news-oots-18-03-2026.jpg
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March 2026 European Council stresses competitiveness and the importance of the Single Market (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/956172479/illu-news-oots-25-03-2026.jpg
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National coordinators meet during the 59th SDG coordination group meeting (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/956171803/illu-news-oots-23-03-2026.jpg
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The Once-Only view from Finland (OOTSHUB) —FinlandKirsi Mikkonen - Mervi Kylmänen-Paakki - Olli Hurskainenhttps://ec.europa.eu/digital-building-blocks/sites/download/attachments/674509304/interview-card-cover-finland.jpg
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The Once-Only view from France (OOTSHUB) —FranceJonathan J. AttiaFrench CTO for European Single Digital Gatewayhttps://ec.europa.eu/digital-building-blocks/sites/download/attachments/631047320/interview-card-cover-france.jpg
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The Once-Only view from Portugal (OOTSHUB) —PortugalJorge SousaPortuguese national coordinator for European Single Digital Gatewayhttps://ec.europa.eu/digital-building-blocks/sites/download/attachments/652773269/interview-card-cover-portugal.jpg
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The Once-Only view from Germany (OOTSHUB) —GermanyChristoph Harnoth - Sybille Behlinghttps://ec.europa.eu/digital-building-blocks/sites/download/attachments/694486760/interview-card-cover-germany.jpg
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Watch Once-Only Studio interview with Croatian SDG team (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/924975280/interview-card-cover-portugal.jpg
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Directorate General for Higher Education officially becomes Once-Only evidence provider (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/924975150/illu-news-oots-13-10-2025.jpg
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Competitiveness is at the top of the EU’s agenda: why “Once-Only” is essential (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/947486842/illu-news-oots-05-02-2026.jpg
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Once-Only Services going-live! SDG procedures in production in Croatia (setting up a business, doing an income tax return and applying for studies) (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/952468703/illu-news-oots-02-03-2026.jpg
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Commission releases version 2.0 of the OOTS Technical Design Documents (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/952471419/illu-news-oots-05-03-2026.jpg
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SDG national coordinators discuss the road ahead in first OOTS Coordinators Café (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/946733242/illu-news-oots-04-02-2026.jpg
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"Once-Only" steers Europe towards simpler cross-border processes for a better Single Market, in line with the EU Competitiveness Compass (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/881983974/illu-news-oots-07-02-2025.jpg
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Watch Once-Only Studio interview with Finnish SDG team (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/891322871/illu-news-oots-08-04-2025.jpg
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Austria talks about synergies between "Once-Only" and the EUDI Wallet (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/905219262/illu-news-oots-08-07-2025.jpg
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Digital Commission Awards: Once-Only wins for Team demonstrating the most multidisciplinary approach for digital-ready policymaking (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/887382196/illu-news-oots-19-03-2025.jpg
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Re-live ‘Europe goes Once-Only – Lithuania edition’ – aftermovie! (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/902433610/illu-news-oots-16-06-2025.jpg
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Once-Only Studio presents: a conversation with Lithuania (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/909707471/illu-news-oots-07-08-2025.jpg
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Watch Once-Only Studio interview with Spanish SDG team (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/920060264/illu-news-oots-16-09-2025-cta.jpg
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Re-live ‘Europe goes Once-Only - Portugal edition’ with the official aftermovie (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/924977246/illu-news-oots-31-10-2025.jpg
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Your Europe celebrates five years of free, accurate information and support for your life and business in the EU (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/935395782/illu-news-oots-16-12-2025.jpg
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From Once-Only Principle to the EU Digital Identity Wallet: how Europe is simplifying digital public services (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/940311615/illu-news-oots-18-01-2026.jpg
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eDelivery AS4 2.0 interoperability testing (8 December 2026) (eDelivery User Community) —
online | 8 December 2026
Do you have an eDelivery AS4 2.0 solution? Register for interoperability testing
If you are implementing eDelivery AS4 2.0, we invite you to participate in our event. The 2026 edition of eDelivery AS4 2.0 interoperabilty testing will take place just around the time the conformance testing service should support eDelivery AS4 2.0.
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Finnish SDG Team Present Nordic-Baltic OOTS 2.0 project at SEMIC 2025 (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/930453289/illu-news-oots-08-12-2025.jpg
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Once-Only Services going-live! Change of competent authority for air traffic controllers in Italy (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/935396425/illu-news-oots-18-12-2025.jpg
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Two systems one vision: OOTS-EUDI Wallet synergies final report published (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/930453293/illu-news-oots-09-12-2025.jpg
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OOTS go-live announcement – Lithuania (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/930449095/illu-news-oots-25-11-2025.jpg
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“Europe Goes Once-Only – Croatia edition” brings a simpler Single Market to the southeastern EU (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/930451374/illu-news-oots-01-12-2025.jpg
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Commission Publishes 2026 Work Programme, Driving Forward Simplification Agenda (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/929202632/illu-news-oots-10-11-2025.jpg
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“Quality of Public Administration Toolbox for Practitioners” recommends Once-Only to EU Member States (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/929202440/illu-news-oots-10-11-2025.jpg
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OOTS Community meets during 17 Implementers Café (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/924976619/illu-news-oots-27-10-2025.jpg
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October 2025 European Council calls for Simplification to lead EU Competitiveness Agenda (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/924976587/illu-news-oots-24-10-2025.jpg
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Updates to Once-Only ‘Acceleratormeter – Portugal and Latvia progress (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/924975703/illu-news-oots-17-10-2025.jpg
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CEF eDelivery and eInvoicing DSI Stakeholder Days (Digital) — We invite you to be part of the CEF eDelivery & eInvoicing Stakeholder Days, which are to be held on 29 November – 1 December 2016
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How “Once-Only” is at the heart of a ‘28th Regime’ in the EU’ (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/920064190/illu-news-oots-03-10-2025.jpg
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“Europe goes Once-Only – Portugal Edition" accelerates integration of national Competent Authorities, September 2025 (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/920063611/illu-news-oots-01-10-2025.jpg
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Dutch national coordinator publishes OOTS Common Services Query Validator (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/920063579/illu-news-oots-01-10-2025.jpg
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State of the EU 2025: a more competitive Europe in testing times (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/915933156/illu-news-oots-12-09-2025.jpg
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16th OOTS Implementers' Café Webinar Sets the Stage for Upcoming Conferences in Lisbon and Zagreb (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/915933183/illu-news-oots-12-09-2025-ic16.jpg
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The challenge of implementing modern Cloud infrastructure Lessons from the Once-Only Common Services Cloud experience (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/915931574/illu-news-oots-28-08-2025.jpg
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Recent event “Towards a Simpler Single Market” sings praises of the Once-Only Technical System (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/908526049/illu-news-oots-16-07-2025-1.jpg
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Commission publishes event report for the #6 Once-Only Technical System Projectathon (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/908525670/illu-news-oots-14-07-2025.jpg
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Member States debrief #6 Once-Only Technical System Projectathon and prepare the next ‘Europe goes Once-Only’ event in Portugal (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/905217281/illu-news-oots-01-07-2025.jpg
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EU Member States move towards live transactions in sixth OOTS Projectathon (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/902433564/illu-news-oots-16-05-2025.jpg
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Commission organises webinar on building a sovereign and secure digital future – How DIGIT can help you become a digital innovator (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/900015970/illu-news-oots-23-05-2025.jpg
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First Version of Once-Only Technical System goes into Production in Finland (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/896827582/illu-news-oots-06-05-2025.jpg
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Tuesday 26th of July - Live Webinar: "CEF eDelivery - What's In It For You?" (Digital) — Thank you to all who attended the webinar. We hope it proved useful in clarifying your understanding. For those of you who couldn't attend, or who wish to re-listen, below you will find recordings of each segment of the webinar.
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Once-Only means a simpler, more resilient digital environment in Europe (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/892470445/illu-news-oots-16-04-2025.jpg
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Member States take stock between milestone events in #14 OOTS Implementers Café (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/894304673/illu-news-oots-24-04-2025.jpg
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Major success as Member States and Competent Authorities gather in Vilnius, Lithuania (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/894304266/illu-news-oots-18-04-2025.jpg
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Citizen forums show how the Once-Only Technical System can save students time and money (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/887384412/illu-news-oots-01-04-2025.jpg
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Once-Only goes local, 2025 (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/887383475/illu-news-oots-27-03-2025.jpg
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Lithuania prepares to roll out the Once-Only Technical System (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/887381888/illu-news-oots-18-03-2025.jpg
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General Report on the Activities of the EU 2024 shows value of “Once-Only” (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/887381485/illu-news-oots-14-03-2025.jpg
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Germany progresses on national-Once-Only Technical System (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/887380245/illu-news-oots-06-03-2025.jpg
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How Europe will go “Once-Only” in 2025 – updates from 13th Implementers’ Café (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/883824996/illu-news-oots-20-02-2025.jpg
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2025 Commission work programme puts simplification in the spotlight (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/883824247/illu-news-oots-17-02-2025.jpg
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Register now: Europe goes Once-Only - Lithuania edition (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/881983883/illu-news-oots-06-02-2025.jpg
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Gateway Coordination Group discusses Once-Only in the year ahead (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/881983728/illu-news-oots-05-02-2025.jpg
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Commission launches development of new Technical Support Dashboard (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/875855875/illu-news-oots-24-01-2025.jpg
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Single Market Strategy 2025 Call for evidence January 2025 (OOTSHUB) —https://ec.europa.eu/digital-building-blocks/sites/download/attachments/864335488/illu-news-oots-07-01-2025.jpg
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eDelivery at Peppol Conference Europe 2026 (16 & 17 June 2026) (eDelivery User Community) —
Brussels | 16 & 17 June 2026
Come to talk to eDelivery at Peppol conference: digital trade is the 2026 theme
We will be present at OpenPeppol's largest global gathering of policymakers, Peppol Authorities, service providers, industry leaders and digital trade experts. Its slogan is "Shaping the future of interoperable Digital Trade".
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CEF Building Blocks Presented at Internet of Things (IoT) World Congress 2018 (Digital) — The current lack of ICT platform standards to manage such information means an obstacle for the development of Smart Digital Services.
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Connecting Europe: CEF Building Blocks Presented at eDelivery Day in Sweden (Digital) — Sweden has made significant progress in the deployment of eDelivery infrastructure at the creation of a vibrant digital ecosystem around it.
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CEF Building Blocks Presented at the Swedish Conference eFÖRVALTNINGSDAGARNA (Digital) — The event ran over two days, filled with the latest information regarding e-government and digital transformation.
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CEF Building Blocks Presented at the German Federal Office of Administration (Digital) — The BVA has a history of close cooperation with the European Commission, and Member States' authorities.
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