Once-Only Principle (Procurement)

The Once-Only Principle is one of the core objectives of European digital government reform. In procurement, it means that a supplier who has already provided a certificate (such as a tax clearance certificate, a company registration extract, or an insurance certificate) to one contracting authority should not have to provide the same document again to a different authority, or even to the same authority for a different contract. The information should be stored, verified once, and shared electronically between the parties who need it.

What is the Once-Only Principle in Procurement?

The Once-Only Principle (OOP) in the EU context derives from the EU eGovernment Action Plans and is now embedded in the Single Digital Gateway Regulation (EU 2018/1724). In procurement, its practical expression is most visible through the European Single Procurement Document (ESPD), which allows suppliers to self-declare their eligibility and suitability in a structured electronic format, with verification of evidence deferred to the award stage and (in principle) reused across different procedures.

The principle operates at two levels. At the supplier level, completing and reusing an ESPD avoids submitting the same certificates and declarations with every bid. At the system level, contracting authorities and accredited databases are supposed to exchange evidence electronically rather than requiring suppliers to obtain fresh certified copies of documents for each procedure. The e-Certis system, maintained by the European Commission, maps the types of evidence required across member states and links to the national databases or issuing bodies where each certificate can be retrieved.

The technical realisation of OOP in procurement is still progressing across Europe. Some member states have connected their national supplier databases (such as the French DUME or the Dutch TenderNed pre-qualification system) to allow buyers to query evidence directly, without asking suppliers to upload it. Fully automated cross-border evidence exchange remains a medium-term goal rather than a universal reality.

Under the UK Procurement Act 2023, the Central Digital Platform is intended to enable suppliers to maintain a single profile of information that can be shared with multiple buyers, reducing the repetition of providing the same company information for each tender. This is the UK's equivalent implementation direction.

Why it matters for bidders

For suppliers that bid regularly across multiple public sector buyers and multiple countries, the administrative burden of repeatedly gathering and certifying the same supporting documents is substantial. The Once-Only Principle, even in its current partial implementation, reduces this burden in several ways:

• A saved ESPD or equivalent self-declaration can be reused and updated for new procedures rather than completed from scratch.
• In countries with connected evidence databases, the buyer retrieves certificates directly, removing the need to obtain fresh certified translations or notarised copies.
• Supplier registration data held on a national portal can be pre-populated into bid forms, reducing manual data entry.

Monitoring which countries and platforms have implemented OOP capabilities (even partially) is worthwhile for regular bidders in those markets.

Example

A Danish IT consultancy regularly bids on ICT contracts across Denmark, Sweden, and Finland. In Denmark, the national procurement portal integrates with the Danish Business Authority's company register, so the buyer can retrieve the supplier's registration and financial data directly. In Sweden, the platform allows the supplier to reuse their previously submitted ESPD with only the procedure-specific sections updated. In Finland, they must still upload fresh certificates. The Danish and Swedish implementations demonstrate OOP in practice; Finland is still transitioning.

Frequently Asked Questions

Is the Once-Only Principle fully implemented across Europe?

No. Implementation is uneven. Some member states (particularly the Nordic countries and the Netherlands) have made significant progress. Others still require suppliers to upload fresh evidence for each procedure. The European Commission continues to develop e-Certis and related infrastructure, but full cross-border OOP for procurement evidence remains a work in progress.

Does the ESPD fully implement the Once-Only Principle?

The ESPD implements OOP at the self-declaration level: you declare your situation and qualifications once (per procedure), and the contracting authority accepts that declaration in lieu of certificates at the selection stage. Full OOP would go further, enabling authorities to retrieve the underlying certificates from registries directly. The ESPD is a step toward OOP, not its complete realisation.

What is e-Certis and how does it help suppliers?

e-Certis is a free online tool maintained by the European Commission that maps the types of certificates and supporting documents required by contracting authorities in each EU member state. For each certificate type, it identifies the issuing body and, where available, links to online databases where the certificate can be retrieved. Suppliers bidding cross-border can use e-Certis to understand what evidence will be required and where to obtain it.