The European Commission is inviting evidence on how the advertising libraries maintained by the largest online platforms should work. The exercise could change the accessibility and usefulness of information about paid promotions, but it does not introduce a new set of advertising rules today.
Advertising transparency is moving from a broad legal principle towards a more detailed discussion about how online platforms disclose their commercial activity. The European Commission opened a call for evidence on advertising repositories on Wednesday, giving industry representatives, researchers and civil society until 2 December to comment on forthcoming technical guidelines.
Under Article 39 of the Digital Services Act, very large online platforms and very large online search engines must maintain publicly accessible repositories of advertisements displayed through their services. Those repositories are intended to show what was advertised, who paid for it, when it appeared, its reach and the principal criteria used to select its audience.
The new consultation concerns whether these libraries are sufficiently useful in practice. It is not a proposal to require every European business to create its own advertising database, and it should not be confused with the EU’s separate rules on political advertising.
Why the technical details matter
Transparency has limited value if information exists but cannot readily be found or analysed. A company researching a competitor’s campaign, an investigator examining misleading promotions and a regulator tracing advertisements for illegal products may all need to search a platform’s repository. Their requirements differ from those of an ordinary user viewing a single advert.
The Commission is therefore seeking views on three practical matters: making repositories easy to search, explaining how audiences are targeted and reached, and ensuring the advertising content itself is accessible.
Search functionality is particularly important. Repositories can contain vast numbers of advertisements. Inconsistent terminology, short retention periods, incomplete fields or weak search facilities can prevent users from drawing meaningful comparisons even when a platform formally provides the required information.
For professional communications teams, the issue is not simply regulatory compliance. More reliable advertising libraries could provide greater visibility into campaigns, commercial claims and competitors’ public messaging. They may also expose weaknesses in how advertisers document the origin and purpose of promotions.
Who carries the legal responsibility?
The relevant DSA duty applies to providers designated as very large online platforms or very large online search engines. It is not an identical obligation imposed on every advertiser, agency or publisher.
Nevertheless, brands and agencies supply much of the information that appears in advertisements and associated campaign records. If the Commission’s eventual guidance improves consistency in how platforms describe sponsors, targeting criteria or reach, marketing teams may encounter more detailed requests for information from their advertising partners.
Companies operating across several platforms could benefit from clearer standards, although the eventual operational requirements will depend on the final guidelines and each provider’s implementation.
Agencies should also distinguish the advertiser, the entity paying for an advert and the organisation responsible for the claims it contains. These roles can differ, particularly where international groups, distributors, intermediaries or advertising accounts managed on behalf of clients are involved.
A well-maintained campaign record can make those distinctions easier to explain if a complaint, investigation or reputational dispute arises.
Commercial benefits and competitive concerns
Greater transparency can improve scrutiny of misleading commercial practices, scams and illegal products. It may also help advertisers identify impersonation campaigns or unauthorised use of their brands.
But disclosure can generate commercial concerns. Advertisers may fear that rivals will gain insights into campaign strategies, audiences and creative testing. Platforms may have to balance public access with personal data protection, security and legitimate confidentiality.
The DSA establishes the legal framework. The Commission’s technical guidance will need to clarify how to make repositories effective without turning them into unrestricted sources of sensitive operational information.
There is also a question of comparability. A database designed differently on every platform makes cross-platform research more difficult. The Commission’s initiative offers an opportunity to explore common approaches, though a consultation alone does not guarantee standardisation.
What should organisations do now?
For agencies and brands using major digital advertising services, the immediate task is to understand what campaign information their platforms already disclose. Communications teams can review sponsor identities, payment arrangements, targeting documentation and the consistency of advertisements with substantiated product claims.
They should also ensure that legal, compliance and marketing colleagues agree on responsibility for responding when incorrect or misleading information appears in a repository.
Businesses with direct experience of advertising libraries can contribute to the Commission’s consultation, especially where search limitations or inconsistent data prevent effective analysis.
The call for evidence closes on 2 December 2026. A further targeted consultation is scheduled for 2027, and the Commission currently plans to publish the guidelines in the second quarter of 2028.
That timetable matters: the latest initiative is about shaping future guidance, not announcing an immediately enforceable technical standard.
For communications professionals, the broader development is clear. Advertising transparency is becoming part of the operational infrastructure of digital marketing. The organisations best prepared to manage it will be those that can document not only what they advertise, but who authorised it, how it was distributed and what evidence supports its claims.
