Europe requires large platforms to publish who paid for ads

The test

The EU's Digital Services Act, published in the Official Journal on 27 October 2022, requires providers of very large online platforms and search engines that carry ads to compile a public, searchable repository of those ads. Article 39 states the repository must be reachable through the platform's interface and an API, must stay available for the full period an ad runs plus one year after, and must not contain personal data about the people it could have reached. The duty attaches only once a service is formally designated, a status the European Commission's own guidance page says applies to services with more than 45 million monthly EU users.

What the evidence says

Article 39 lists the minimum contents of each entry: the ad's content and subject, who it ran for, who paid if different, the period shown, whether it targeted specific groups and on what parameters, and, where applicable, recipients reached, by member state. Where a platform removed an ad for alleged illegality, the regulation substitutes a narrower statement of reasons for the withheld sponsor and payer fields. The Commission's page adds the surrounding mechanics: a platform has four months from designation to comply, and being transparent as regards advertising is one of several obligations, alongside recommender-system and moderation transparency, that designation brings. Neither document states a compliance date for any one platform; that depends on designation timing, which this record does not establish.

The sample and the variance

This describes a binding legal requirement, not a platform's own repository or an audit of what one contains. The duty applies only to services the Commission has designated very large, a status tied to measured user count, not revenue, influence or an ad category's sensitivity. It also does not guarantee completeness: the text asks providers to make reasonable efforts toward accuracy, language assuming some margin for error rather than promising an audited dataset.

What to try next

A researcher, marketer or observer using a designated platform's repository can treat Article 39's field list as a checklist, flagging any ad missing sponsor, payer, targeting or reach data as a possible gap rather than assuming completeness by design. This is an editorial reading, not a certification: the regulation sets the minimum a repository must contain, not how complete any platform's implementation actually is.

• Has the platform in question actually been designated a very large online platform, and when did its four-month compliance window begin?
• Does the specific ad entry include the targeting parameters Article 39 requires, or only the sponsor and content fields?
• Where an ad has been removed for alleged illegality, does the repository substitute the narrower statement of reasons the regulation allows?

The Digital Services Act's own text and the European Commission's guidance describe what a public ad repository must legally contain; whether a specific platform's repository meets that bar is a separate, checkable question the regulation does not itself answer.