Under Horizon Europe, gold open access lets grantees claim Article Processing Charges (APCs) as an eligible cost when publishing in a fully open access journal, while green open access requires no APC but demands immediate deposit of the accepted manuscript in a repository — Horizon Europe permits no embargo period on either route. The route chosen changes what a grant can reimburse, not whether the underlying obligation to provide open access is met.
Horizon Europe open access policy is the European Commission’s mandate, set out in the Horizon Europe Model Grant Agreement, requiring immediate open access to peer-reviewed publications arising from EU-funded research, with no embargo and a Creative Commons Attribution (CC BY) licence as the default. This article resolves the specific pre-award question research administrators and principal investigators raise most often: which route — gold or green — is cheaper, faster to budget, and lower-risk to comply with.
- What does the gold open access route require and cost?
- What does the green open access route require, and is there really no embargo?
- Gold vs green: how APC reimbursement actually differs
- Common questions on Horizon Europe open access requirements
- What this means for grant budgeting and compliance teams
What does the gold open access route require and cost?
Gold open access means publishing the final version of record directly in a journal or platform that is open access from the moment of publication. Under Horizon Europe, APCs for publishing in a fully open access journal are an eligible cost and can be charged to the grant budget, provided the journal is genuinely open access rather than a subscription title offering a paid open option.
The European Commission’s Horizon Europe Annotated Grant Agreement draws a firm line here: APCs paid to hybrid journals — subscription journals that unlock a single article for a fee — are not an eligible cost unless the journal is covered by an institutional transformative agreement the funder recognises. Grantees who publish gold must still deposit a copy of the final published version, and its metadata, in a trusted repository at the time of publication; paying the APC does not remove the deposit obligation.
A cost-free variant of the gold route exists: Open Research Europe (ORE), the European Commission’s own peer-reviewed publishing platform for Horizon Europe and Euratom beneficiaries. ORE carries no APC for eligible authors, publishes under CC BY, and satisfies the immediate-access requirement without a grant budget line at all.
What does the green open access route require, and is there really no embargo?
Green open access means publishing as normal — including in subscription or hybrid journals — and separately depositing a copy of the work in a trusted repository so readers can access it without a subscription. Because no APC is typically paid, the green route carries no direct cost to reimburse, which is its main budgetary appeal.
The compliance burden shifts instead to timing and rights. Horizon Europe’s Model Grant Agreement requires the author’s accepted manuscript (AAM) — the final peer-reviewed text before typesetting — to be deposited and made publicly accessible immediately on publication, with no embargo permitted. This is stricter than many national funder policies, several of which still allow embargoes of six to twelve months for the green route. Grantees must also apply a CC BY licence to the deposited manuscript, which means notifying the publisher of their funder obligations at submission, since standard subscription-journal copyright transfer agreements do not grant this right automatically.
Retaining the necessary rights is the single most common green-route compliance failure. Institutions increasingly rely on rights-retention strategies — asserting a CC BY licence on the AAM ahead of acceptance — to avoid publisher pushback after the fact.
Gold vs green: how APC reimbursement actually differs
The financial and compliance trade-offs are distinct enough that they warrant a direct route-by-route comparison rather than treating “open access compliance” as one undifferentiated obligation.
| Factor | Gold open access | Green open access |
|---|---|---|
| APC reimbursement | Eligible for fully open access journals and platforms; must be budgeted in the grant | Not applicable — no APC in most cases |
| Hybrid-journal APCs | Not eligible, unless covered by a recognised transformative agreement | Not relevant — publish anywhere, then self-archive |
| Embargo allowed | Not applicable — immediate by definition | None permitted under Horizon Europe |
| Version deposited | Final published version (Version of Record) | Author’s Accepted Manuscript |
| Licence required | CC BY (CC BY-NC/ND permitted for monographs) | CC BY on the deposited manuscript |
| Zero-cost option | Open Research Europe (no APC) | Always zero-cost by design |
For grant budgeting, this comparison has one practical consequence: a grantee who assumes any APC is reimbursable, or that green deposit can wait for a standard embargo, will fall out of compliance. Horizon Europe’s no-embargo rule on green deposit is stricter than UKRI’s REF-era transitional allowances and than several national mandates still permitting embargoes — a distinction that trips up researchers moving from a previous funder’s rules onto a Horizon Europe grant.
Common questions on Horizon Europe open access requirements
What are the open access requirements for Horizon Europe?
Horizon Europe requires all peer-reviewed scientific publications resulting from funded work to be made immediately open access, with no embargo, under a CC BY licence (or CC BY-NC/ND for monographs). This applies whether the grantee chooses the gold or green route, and a repository deposit is required in both cases.
What is the European Commission’s open access policy under Horizon Europe?
The Commission’s policy treats open access as the default expected outcome of publicly funded research, not an optional extra. It requires immediate access, open licensing, and open metadata, and extends beyond publications to FAIR research data underpinning them, governed by the grant’s Data Management Plan.
Is open access always free for the author?
No. Gold open access typically involves an APC, which Horizon Europe treats as an eligible grant cost only for fully open access venues. Green open access is generally free, since it relies on self-archiving rather than a publication fee, making it the lower-cost default where budget is constrained.
What is an open access policy, in funder terms?
An open access policy is a funder’s binding condition that research outputs be made freely accessible and reusable, typically specifying the timing (immediate vs embargoed), licence type, and eligible cost treatment. Horizon Europe’s version is among the strictest in Europe because it removes the embargo option entirely.
What this means for grant budgeting and compliance teams
Research offices preparing a Horizon Europe proposal should budget APCs only against fully open access venues or confirmed transformative agreements, and should not assume hybrid-journal costs will be reimbursed. Where budget certainty matters more than journal choice, green open access or Open Research Europe removes APC risk entirely while still meeting the immediate-access mandate.
Compliance teams should build rights-retention language into author guidance before submission, not after acceptance, since the no-embargo rule leaves no room to negotiate access timing with a publisher post hoc. Institutional repository workflows that trigger deposit reminders at the point of acceptance — rather than publication — reduce the risk of missing the immediate-deposit requirement.
As the European Commission continues to expand Open Research Europe’s remit and cOAlition S partners refine rights-retention model policies, the practical gap between the two routes is likely to narrow further on cost but remain wide on process — gold trades money for simplicity, green trades cost for rights-management discipline.
