Open access is not optional in Horizon Europe. It is a legal obligation embedded in the Grant Agreement — one that applies to every beneficiary, across every project, from the moment the first publication is produced.
Yet it remains one of the most consistently misunderstood compliance areas in the programme. Many research teams treat it as an afterthought, address it superficially in proposals, and discover its practical implications only when a publication is ready to submit — or when a reviewer or auditor asks for evidence of compliance.
This article explains what open access means in Horizon Europe, what is mandatory, what is recommended, and what the consequences of non-compliance look like in practice.
What open access means in Horizon Europe
Open access in Horizon Europe is part of a broader open science framework. Open science practices are an integral part of Horizon Europe’s framework, designed to foster transparency, accessibility, and reproducibility in research.
Within this framework, the requirements fall into two categories. Mandatory requirements include providing open access to publications, creating data management plans, and reporting publications and datasets. Recommended practices, while not obligatory, include pre-registering studies and sharing methodologies.
Understanding the distinction between mandatory and recommended is essential. Failing to meet mandatory requirements is a compliance breach with direct consequences. Not following recommended practices does not constitute non-compliance, though it may affect how the project is assessed in reviews.
Open access to publications: what is mandatory
All peer-reviewed scientific publications arising from Horizon Europe funding have to be made available in open access. This implies that publications are to be made freely available online, immediately upon publication and with no restrictions on use, by depositing them on a repository.
The key word is immediately. Open access to scientific publications must be immediately available — no embargo periods are permitted. Only costs for immediate open access publishing models are eligible. Hybrid journals are generally not eligible.
There are two compliant routes to open access publication:
Gold open access: Publishing in a fully open access journal or platform, where the published version is immediately freely available. Article Processing Charges (APCs) for fully open access journals are eligible project costs — but only if incurred during the project period.
Green open access: Self-archiving the accepted manuscript (the final peer-reviewed version before publisher formatting) in a trusted repository. In both cases — whether publishing in an open access journal or self-archiving — you must deposit your publication in a repository, even when publishing in an open access journal.
The licensing requirement is specific. Beneficiaries must ensure that at the latest at the time of publication, open access is provided via a trusted repository to the published version or the final peer-reviewed manuscript accepted for publication under the latest available version of the Creative Commons Attribution International Public Licence (CC BY) or a licence with equivalent rights.
For longer text formats — monographs, edited volumes, books — Horizon Europe mandates immediate and full open access. Authors must attach a Creative Commons Attribution Non-Commercial/Non-Derivatives licence to their work.
One important clarification: open access does not create an obligation to publish. Protection measures such as patents take precedence. If a result is being protected through intellectual property mechanisms, the open access obligation does not override that protection. But once a decision to publish has been made, the open access requirement applies in full.
Research data management: the Data Management Plan
Beyond publications, Horizon Europe requires beneficiaries to manage their research data in accordance with open science principles — and to document how they are doing so in a Data Management Plan (DMP).
The DMP is a living document. An initial version must be submitted within the first six months of the project, and it must be updated at each reporting period and at the end of the project to reflect what has actually happened with the data.
The application form includes sections corresponding to a data management plan — covering data type and size, persistent identifiers, intellectual property rights, interoperability, licences, data curation, and responsibilities for data management. Although an actual DMP is not yet required at the proposal stage, applicants should be clear, detailed, and precise, justify their choices, and describe how the FAIR principles are implemented.
The FAIR principles — Findable, Accessible, Interoperable, Reusable — are the framework against which data management is assessed. A DMP that does not address these principles in a meaningful way will not pass a project review.
Research data: open by default, with exceptions
In Horizon Europe, research data should be made open access by default and licensed under the latest version of CC BY or CC0, or equivalent. However, it is recognised that data should be “as open as possible, as closed as necessary”, and exceptions can be made when providing open access to data is against the beneficiary’s legitimate interests, including regarding commercial exploitation; is contrary to other constraints such as data protection rules, privacy, confidentiality, trade secrets, or intellectual property rights; or would be against other obligations under the Grant Agreement.
This “as open as possible, as closed as necessary” principle is important. It means that opting out of open data sharing is possible — but it must be explicitly justified in the DMP, not simply assumed. A project that generates commercially sensitive data, personal data, or data subject to security restrictions can legitimately restrict access, provided the reasoning is clearly documented.
Open Research Europe: the Commission's publishing platform
The European Commission provides Open Research Europe (ORE) as a dedicated open access publishing platform for Horizon Europe projects. Its use is voluntary, but it is designed to make compliance straightforward — publications on ORE are immediately open access and meet all Horizon Europe licensing requirements automatically.
Importantly, ORE is a publishing platform, not a repository. Publications submitted to ORE still need to be deposited in a trusted repository for full compliance.
How open science appears in proposals and reporting
Open science is not just a post-award compliance obligation — it affects how proposals are written and evaluated.
The open science perspective should be considered in several sections of the application form, particularly in the methodology section. Applicants should describe how appropriate open science practices are incorporated as an essential part of the proposed research methodology, and how the selection and implementation of open science practices are tailored to the nature of the work to better achieve the project’s objectives.
In reporting, beneficiaries must declare all publications produced during the project, confirm their open access status, and report on datasets generated and shared. These declarations are reviewed by the Project Officer and form part of the evidence base for the technical report assessment.
Inconsistencies between what was promised in the proposal’s open science section and what was actually done — or failures to deposit publications in a repository — are flagged during reviews and can affect the project’s overall assessment.
What happens if open access obligations are not met
Non-compliance with open access requirements is a breach of the Grant Agreement. The consequences range in severity:
At reporting time: The Project Officer may flag the non-compliance and request corrective action. Publications that are not made open access may be considered non-compliant outputs — affecting the overall assessment of the reporting period.
During a project review: Systematic failure to comply with open access requirements can contribute to a negative review outcome, potentially triggering additional monitoring or, in serious cases, affecting payment.
During an audit: Open access compliance is part of the broader compliance picture assessed in financial and technical audits. Evidence of publication deposits, DMP updates, and repository links may be requested.
In practice, most open access non-compliance issues arise from administrative oversight rather than deliberate breach — a publication deposited in the wrong repository, an embargo applied incorrectly, or a DMP that was never updated after the initial submission. These issues are generally correctable, but they require active management throughout the project.
Final thoughts
Open access in Horizon Europe is not a bureaucratic checkbox. It is a legal obligation that runs through the Grant Agreement from day one to the final report — and beyond, given the audit exposure that extends after project closure.
The teams that manage it well are those that build open science practices into their workflow from the start: flagging publications for deposit as they are accepted, updating the DMP at each reporting period, and maintaining the evidence trail that demonstrates compliance continuously rather than reconstructing it under pressure before a deadline.
For coordinators managing multiple partners across a project, ensuring that all beneficiaries are meeting their open access obligations — not just the coordinating organisation — adds another layer of operational complexity. Kronis PMO provides the structure to track these obligations across the full consortium, so that compliance evidence exists when it is needed rather than being chased at the last minute.
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