The EU's new political ad repository: who sees what, and what to seal

A library for political ads

The repository works like a library card catalogue. When a political ad runs online, its transparency notice is filed in the repository ^[1]. Anyone can search it: journalists checking who funded a campaign, researchers tracking spending or voters wanting to know who is behind the message on their screen.

The regulation behind it, (EU) 2024/900, has applied since 10 October 2025 ^[2]. It says political advertising must be labelled as such and carry a transparency notice, accessible directly from the ad. That notice must state who paid for it, which election or referendum it relates to, how much was spent and whether targeting was used. The repository is where those notices end up.

What the repository holds

Each notice includes the sponsor's name, contact details and registration number if they have one, the amount spent or estimated value, the election or referendum the ad concerns, whether targeting was used and, if so, the main parameters ^[2]. If the ad used personal data for targeting, the notice also states the legal basis.

For ads on very large online platforms under the Digital Services Act, the repository pulls data from the platform's own ad library. For others, the provider of the ad service files the notice ^[1].

The repository went live on 9 October 2026, one day before the regulation's application date ^[1]. It covers ads placed from that date onward.

Who has to ask, and who has to keep records

Any provider of political advertising services—ad agencies, PR firms, political consultants, platforms, influencers and publishers—must ask the sponsor whether a campaign counts as political advertising under the regulation's definition ^[2]. If it does, they must keep the prescribed information for seven years.

The definition is specific: advertising with the purpose of promoting or opposing a party, candidate or idea in the context of an election or referendum, or advertising likely to influence the outcome ^[2]. Not every ad about a policy issue is political advertising, but when it is, the transparency rules apply.

Targeting using personal data online requires that the data was collected from the person, that they gave explicit consent to receive political ads and that no profiling with sensitive personal data was involved ^[2].

What this means for you

If you run political ads, check three things. First, does your ad service provider know it is a political campaign, and have they filed the transparency notice? Second, have you kept a copy of the notice yourself, and can you show what it said on the day the ad ran? Third, if you used targeting, can you document the legal basis and the parameters?

If you provide ad services, the question is simpler: did you ask? The regulation requires you to ask the sponsor whether the service relates to political advertising, and to store the information. A sponsor's denial does not relieve you if the ad was in fact political.

The repository makes non-compliance visible. A missing notice, an incomplete one or one that contradicts what the ad actually showed can be checked by anyone with an internet connection.

How a digital witness fits here

When a campaign is questioned months later, what matters is not just that a transparency notice existed, but that you can show what it said and when it was published.

Here, the thing to seal is the notice itself, the final ad creative as it ran and, if AI was used to generate parts of the campaign, a record of what was generated and approved. Sealing takes a fingerprint of each file or record, not the content, so nothing leaves your systems. The fingerprint goes to WitniumChain, which returns a witness ID. Later, anyone you share the record with can check that the fingerprint still matches.

What it shows: that the transparency notice, the approved creative and the generation record existed at the times you say, unchanged since they were sealed.

What it doesn't: it doesn't show that the notice was adequate, that the ad was lawful or that you complied with targeting rules. It also doesn't replace filing the notice with the repository.

You can seal records as you go—briefs, AI generations, client approvals and final cuts—using the REST API, the SDK or the MCP server, as part of your workflow. The first 2,000 witnesses a month are free. Read more in the documentation.

What to watch

The regulation's penalties can reach 6 per cent of a sponsor's or provider's annual income or budget, or 6 per cent of global annual turnover ^[2]. National authorities will enforce it, and their decisions will show how strictly incomplete or missing notices are treated.

The repository itself is new, and how it handles corrections, disputes or notices filed late will become clear as cases arise. For now, the rule is straightforward: every political ad online needs a transparency notice, and that notice ends up in a place anyone can check.