About OOTSConnect to the Once-Only Technical System to deliver the once-only principle across the EU

The Once-Only Technical System (OOTS) is the EU’s secure infrastructure for government-to-government data exchange across borders ensuring citizens and businesses submit documents just once, without downloading from one authority and uploading to another.

Connecting to OOTS is a legal obligation and the infrastructure is ready

Under the Single Digital Gateway Regulation (EU) 2018/1724(opens in a new tab), connecting to OOTS is a legal requirement if your authority is in scope. Now is the time to connect.

25 Key Procedures

From studying, to moving, to retiring, to doing business, the Single Digital Gateway Regulation and related EU directives define a broad range of procedures in scope of the once-only technical system.
+1,000 Public Authorities

Join the hundreds of public authorities connecting to the system to deliver the promise of once-only to citizens and businesses.
2023 OOTS live since

The OOTS common services went live in December 2023. Since then, Member States have been building national platforms and connecting their authorities. The system is tested, proven, and ready for your authority.
60 Key Evidences

Request and/or provide one of the 60 key evidences identified for the administrative procedures in scope.

How Once-Only works

Discover with this illustration how citizens and businesses can, with just a few clicks, request official documents and data exchange between public authorities.

Find out more

Experience OOTS

Understand how the Once-Only Technical System connects public authorities so that they can exchange evidence at the request of a citizen or business, by navigating our prototype.

Steps for cross-border procedures

Visit the Once-Only Technical System Step-by-step walkthrough page for a detailed overview of the steps in the Once-Only Technical System (OOTS) journey.

What connecting to OOTS means for your authority

Less manual work for your team

OOTS automates the retrieval of evidence from authorities in other Member States, eliminating the time your staff spend on manual verification and the errors that come with it. For SMEs completing cross-border procedures, OOTS cuts the total process time by an average of 44%.
Protection against fraud

As AI-generated fake identities and documents become an increasing threat to online procedures, OOTS provides a direct line to authentic, verified data from trusted government sources. Every piece of evidence exchanged through OOTS comes directly from the issuing authority, not from the citizen.
Ensures compliance with the SDGR & eIDAS framework

Supports your authority in meeting EU legal requirements for fully online cross-border procedures while adhering to secure electronic identification and trust service standards.
Better outcomes for citizens and businesses

User research shows that over 91% of people who complete a cross-border procedure via OOTS report a better experience. Businesses save an average of €5,247 per cross-border procedure. Connecting your authority delivers measurable results for the people you serve, and for the EU’s broader economic competitiveness.

Supported procedures

These are some of the administrative procedures and kinds of evidence currently supported by the Once-Only Technical System. Learn about bigger scope of OOTS in the domain use cases.

Education and training
Procedure

Application for tertiary education financing

Financial support to help cover the cost of university studies.

Evidence

Documents required

Proof of secondary education

Proof of university diploma

Proof of enrollment certificate
Education and training
Procedure

Initial admission to public tertiary education

Guiding students through the first step of university enrollment.

Evidence

Documents required

Proof of secondary education
Education and training
Procedure

Academic recognition of diplomas, certificates or other proof of studies or courses

Citizens requesting recognition of their studies.

Evidence

Documents required

Proof of tertiary education diploma

Proof of diploma supplement (EU DS)
Business
Procedure

Notification of business activity

Citizens informing member states of business activity they conduct.

Evidence

Documents required

Proof of business registration

Proof of absence of criminal record
Business
Procedure

Recognition of professional qualifications

Citizens requesting official recognition of their professional and vocational training.

Evidence

Documents required

Proof of business registration

Proof of good professional standing