Understanding the EU Once-Only Principle

The European Union's Once-Only Principle (OOP), formally known as the Once-Only Principle, is a cornerstone of the bloc's digital transformation strategy aimed at streamlining public administration. At its core, the OOP stipulates that citizens and businesses should submit required information to public authorities only once, with that data then reused across different administrations without the need for repeated submissions. This principle emerged as one of the seven key drivers in the European Commission's eGovernment Action Plan for 2016-2020 and was enshrined in the Single Digital Gateway Regulation (EU) 2018/1724.

In practice, the OOP tackles a longstanding pain point for Europe's businesses: excessive administrative burdens that hinder cross-border activities. Small and medium-sized enterprises (SMEs), defined by the EU as companies with fewer than 250 employees and turnover under €50 million, often face fragmented procedures when expanding into other member states. Self-employed professionals, including freelancers and sole traders, encounter similar hurdles in registering businesses, obtaining licenses, or complying with tax requirements abroad. By enabling secure, automated data exchange, the OOP promises to foster a true Single Market, boosting competitiveness and economic growth.

Implemented through the Single Digital Gateway, the OOP covers 21 prioritized cross-border procedures, such as business registration and recognition of professional qualifications. Portals like Your Europe serve as entry points, providing multilingual guidance and linking to national systems.

The Once-Only Technical System: Technical Backbone of OOP

The Once-Only Technical System (OOTS) is the innovative infrastructure powering the OOP's cross-border data exchanges. Launched in December 2023, OOTS acts as a decentralized hub that connects national public administration systems, allowing authorities to request and retrieve standardized documents securely without involving the business or individual repeatedly. Users initiate processes via user-friendly portals, where OOTS handles identification, consent management, and data flows in compliance with GDPR and eIDAS regulations.

Key features include semantic matching of data attributes, evidence logging for audits, and support for the European Digital Identity Wallet. In January 2026, the European Commission announced OOTS as open-source software, inviting member states, developers, and stakeholders to use, modify, and distribute it freely to accelerate adoption. This move aligns with EU efforts to promote digital sovereignty and interoperability.

For businesses, OOTS eliminates manual steps like scanning physical documents, notarizations, translations, and physical visits to authorities. Instead, digital originals are shared instantaneously across borders, transforming cumbersome processes into seamless digital journeys.

Spotlight on the Landmark 2024 Study

A pivotal 2024 study commissioned by the European Commission provides concrete evidence of the OOP's transformative potential. Published in April 2025 as the 'Study on Benefits of the OOTS for SMEs,' it interviewed 43 SMEs and self-employed workers across 18 EU countries, including Germany, France, Portugal, and others from Nordic, Baltic, Southern, and Central Europe regions.

The methodology was rigorous: Participants walked researchers through current cross-border expansion procedures—primarily starting a branch or subsidiary in another EU country—detailing every step, from researching requirements to final registration. Costs and times were estimated holistically, including internal staff hours, external advisors, travel, document handling, and opportunity costs. Researchers then simulated an OOTS-enabled future scenario, quantifying differences. Sectors represented included manufacturing, services, IT, construction, and professional services, ensuring diverse insights.

This qualitative-quantitative approach yielded robust projections, highlighting not just numbers but user experiences and perceived efficiencies.

Time Savings: From Weeks to Days for SMEs

One of the study's standout revelations is the dramatic reduction in time required for administrative procedures. SMEs currently dedicate an average of 14.4 weeks to cross-border setups, encompassing understanding rules (3.2 weeks), gathering documents (4.1 weeks), travel and meetings (2.8 weeks), and follow-ups (4.3 weeks). With full OOTS implementation, this drops to 8 weeks—a 44% reduction, saving 6.4 weeks per procedure.

Self-employed workers fare even better, shaving 10.2 weeks down to 4.8 weeks (53% reduction, 5.4 weeks saved). These gains stem from automating document retrieval (saving 2-3 weeks), eliminating travel (1-2 weeks), and streamlining verifications (1 week).

Cost Reductions: Millions in Potential Savings

Financial impacts are equally compelling. SMEs face average costs of €9,989 today, driven by document preparation (€3,200), professional advice (€2,500), translations/notarizations (€1,800), and travel (€2,489). OOTS cuts this to €4,742, a 53% drop yielding €5,247 savings per instance.

For self-employed, costs fall from €2,576 to €1,068 (59% reduction, €1,508 saved), primarily by bypassing advisors and physical handling. Scaled across Europe's 23 million SMEs, these efficiencies could unlock billions in productivity.

Additionally, the Your Europe portal alone saves SMEs up to 4 weeks and over €2,000 in preliminary research.

Photo by Joshi Milestoner on Unsplash

Testimonials: Businesses Speak on OOTS Benefits

Participants' voices underscore the human impact. A German SME owner enthused, "It would be very nice and convenient to move documents across borders like this." A French self-employed professional exclaimed, "It’s excellent and would be so practical... OOTS would save weeks of time and €4-5,000 for my company!"

• Portuguese self-employed: "Very nice and smooth, totally fits... no need to download anything."
• French SME: "No physical visits or proving identity will save valuable time."

Over 91% agreed cross-border expansion becomes "substantially easier," praising speed, seamlessness, and user-friendliness.

Procedures Transformed: A Step-by-Step Example

Consider a typical scenario: An Italian SME launching a branch in the Netherlands. Currently: (1) Research Dutch rules (online/offline, 3 weeks); (2) Gather Italian registration proof, tax extracts (physical copies, notarized, translated, 4 weeks); (3) Travel to Dutch chamber of commerce (1 week); (4) Submit, await verification (6 weeks). Total: 14+ weeks, €10k+.

With OOTS: (1) Access Your Europe, identify needs (1 week); (2) Consent to share digital docs via OOTS (instant); (3) Dutch authority retrieves directly (no travel); (4) Automated approval (3 weeks). Total: 8 weeks, €5k.Full study details

Implementation Progress and 2026 Milestones

OOTS infrastructure went live in late 2023, with Nordic and Baltic countries pioneering onboarding. By January 2026, the Commission's open-source release and Technical Support Dashboard spurred wider adoption. Enthusiasm is high, with toolkits aiding integration.

Full rollout ties to EU Digital Identity Wallet mandates by 2026, ensuring secure eIDs for all. Challenges like legacy systems persist, but momentum builds toward 100% coverage for key procedures.

Broader Economic Implications for EU Businesses

Beyond numbers, OOP/OOTS catalyzes SME internationalization. Europe's SMEs generate 50% of GDP but lag in exports (37%). Reduced burdens could boost cross-border ventures by 20-30%, per related analyses. Self-employed, numbering millions, gain mobility for gigs, consulting.EC newsroom

For academics and researchers—often self-employed or in small labs—this means easier grant applications, collaborations across borders. Explore opportunities at AcademicJobs research positions or Europe-wide listings.

Challenges, Solutions, and Future Outlook

While promising, hurdles remain: Data privacy concerns, interoperability gaps, and digital literacy. The study notes current reliance on advisors (20-30% costs). Solutions include training, phased rollouts, and wallet integration.

• Privacy: Consent-based, logged exchanges.
• Adoption: Open-source accelerates dev.
• Equity: Support for low-digital SMEs.

By 2030, full OOP could save €10-20 billion annually. As EU pushes competitiveness, OOTS positions Europe as admin-burden leader.

Photo by Marshal Quast on Unsplash

Actionable Insights for SMEs and Self-Employed

Start today: Register on Your Europe for guidance. Monitor national OOTS onboarding. For career shifts involving cross-border moves, like lecturing abroad, consult higher ed career advice. Businesses eyeing expansion? Our higher-ed jobs and university jobs pages link skilled talent efficiently.

Stay informed via AcademicJobs.com, your trusted hub for Europe's professional landscape.