Moving to another EU country: what the once-only system changes

Moving to another EU country has always meant paperwork: proof of who you are, where you lived, what you studied and whether you are covered for healthcare, often as certified copies and sometimes translated. The EU’s Single Digital Gateway Regulation aims to cut that down. Where both countries are connected, a person can ask the authority in their new country to fetch official evidence directly from the authority in their old one, through the Once-Only Technical System (OOTS).¹

This article follows that journey step by step. The full background, including the legal basis and timeline, is in the guide to the once-only principle.

What a move can involve

The Regulation lists the procedures that Member States must offer fully online, where they exist nationally, and groups them by life event.¹ For someone moving, the relevant ones include:

• requesting proof of residence;
• registering a change of address;
• registering a motor vehicle;
• applying for a European Health Insurance Card;
• requesting academic recognition of diplomas, or applying for study financing.

Procedures for recognising professional qualifications are covered too, through the directive on that subject.¹ That matters for nurses, teachers, engineers and anyone else whose work depends on a recognised qualification.

How an exchange works, step by step

The Implementing Regulation sets out the user journey.² In plain terms:

1. Start the procedure. The person begins an online procedure in their new country and is told that using the system is voluntary and that they can preview the evidence first.
2. Sign in. They identify themselves with an electronic identification means notified under eIDAS, the EU framework for electronic identification. See digital identity and eIDAS.
3. Ask for the evidence. They choose which evidence to fetch, see which authority will provide it, and make an explicit request.
4. Preview it. They are redirected to the authority that holds the evidence, which matches their identity against its records, and they see what would be sent.
5. Decide. Only if they agree is the evidence returned to the authority that asked for it.

Two safeguards are worth noticing. The evidence may be used only for the procedure it was requested for, and the person can always submit it another way instead.¹ The system is a convenience, not a requirement.

Where it works today

The legal obligations have applied since 12 December 2023.¹ The Commission states that the central infrastructure has been live since December 2023, while Member States are still implementing their national parts and connecting their authorities, and it tracks their readiness on a seven-level scale.³

So the honest answer to “can I skip the paperwork?” is: sometimes. It depends on whether the authority in the new country and the one holding the evidence are both connected, and whether the evidence exists in a digital form that can be exchanged. The duty to share only applies to evidence an authority already issues electronically in a suitable format.¹

Where people still carry paper

• Identity mismatches. If the authority holding the evidence can’t match the person to exactly one record, the exchange stops.² Different spellings of a name or missing middle names are enough to cause that.
• Evidence that isn’t digital yet. Older records may still exist only on paper, and the rules even provide for a reply saying the evidence is being converted.²
• Different ideas of proof. What counts as proof of residence or of a qualification differs between countries, so authorities have to agree what a document from one country proves in another.

What this means for public bodies

For authorities that receive applicants from other countries, the system changes the design of the form as much as the back office. Every request for a certificate is worth checking against the list of procedures in scope, and every piece of evidence the authority issues itself is worth making available in a form that can be exchanged.

The bigger lesson is the one behind life-event services: a move is one event in a person’s life, but it touches many bodies in two countries. The more of those bodies can exchange evidence, the less the person has to carry.