Plan S green open access is the compliance route that lets a researcher publish in the journal of their choice — including a subscription journal — and still meet their funder’s open access mandate, provided the Author’s Accepted Manuscript (AAM) or Version of Record (VoR) is deposited in a qualifying repository immediately on publication, with no embargo period and under a CC BY licence.
Green open access is repository-based open access: the author (or their institution) self-archives a copy of the peer-reviewed article in an online repository, independently of whatever access model the publishing journal itself uses. Under cOAlition S’s implementation guidance, this route is one of three recognised paths to Plan S compliance, alongside publishing in a fully open access journal/platform and publishing under a transformative arrangement.
- What is green open access under Plan S?
- What are the zero-embargo deposit rules?
- Which repositories qualify?
- How does the green route differ from the Rights Retention Strategy?
- How does green compare with gold and hybrid (APC) routes?
- Frequently asked questions
- What this means for research offices
- Outlook
What is green open access under Plan S?
Green open access under Plan S is the “repository route” to compliance: a researcher publishes in a subscription journal and separately makes a copy freely available in an Open Access repository. It requires no article processing charge (APC), and does not depend on the publisher’s own access model — why research offices generally advise it as the lowest-cost compliance path.
cOAlition S’s Principles and Implementation guidance states: “all scholarly articles that result from research funded by members of cOAlition S must be openly available immediately upon publication without any embargo period.” The green route is one of three ways to satisfy this.
What are the zero-embargo deposit rules?
The defining feature of Plan S green open access is that no embargo period is permitted — not the traditional 6- or 12-month delay still common elsewhere. Deposit and public availability must coincide with the publication date, including for early-view versions published online ahead of an issue.
- Version deposited: either the Author’s Accepted Manuscript (the peer-reviewed, post-review text before publisher copy-editing and typesetting) or the Version of Record, at the publisher’s discretion.
- Timing: immediate — deposit “no later than” publication date; retrospective or embargoed deposit does not satisfy Plan S.
- Licence: the deposited copy must carry a Creative Commons Attribution (CC BY) 4.0 licence by default. cOAlition S accepts CC BY-SA 4.0 or CC0 as secondary alternatives, and will approve CC BY-ND only where a grantee explicitly requests and justifies it.
- Rights basis: the author or their institution must retain sufficient rights — via copyright retention or a compliant licence to publish — to authorise the deposit themselves, rather than relying on publisher permission after the fact.
This zero-embargo condition is what separates Plan S green OA from “traditional” green OA policies used by many institutional mandates (e.g. REF-linked UK policies), which commonly tolerate a delay before the AAM is made public.
Which repositories qualify?
Plan S does not publish a fixed whitelist of approved repositories. Instead, cOAlition S sets published technical criteria that any repository — institutional, subject-based, or general-purpose — must meet, and expects the repository to be listed in the Directory of Open Access Repositories (OpenDOAR) or in the process of registering.
Under Part III of cOAlition S’s technical guidance, mandatory repository criteria include:
- Persistent identifiers (PIDs) for deposited versions, such as a DOI.
- High-quality, interoperable article-level metadata released under a CC0 public domain dedication, including complete funder and grant-number information.
- Machine-readable open access status and licence information embedded in the article record.
- Continuous availability, with uptime of at least 99.7% (excluding scheduled maintenance).
- A functioning helpdesk — at minimum an email address — with a response time of no more than one business day.
In practice, this means most well-run institutional repositories qualify, alongside subject repositories such as PubMed Central and Europe PMC for the life sciences, and general-purpose repositories such as Zenodo (which is itself referenced elsewhere in cOAlition S’s own guidance materials). Research offices should verify a specific repository’s registration status directly via OpenDOAR rather than assuming compliance from reputation alone.
How does the green route differ from the Rights Retention Strategy?
The green route and the Rights Retention Strategy (RRS) are related but distinct mechanisms, and conflating them is a common source of confusion in author-facing guidance. The green route is the compliance pathway — publish anywhere, deposit with zero embargo. RRS is the legal mechanism cOAlition S introduced to make that pathway enforceable even when a publisher’s standard licence-to-publish would otherwise block it.
Under RRS, an author applies a CC BY licence to their AAM at the point of submission — before any publishing agreement is signed — via a standard rights-retention statement in the manuscript or cover letter. This pre-empts publisher terms that would otherwise impose an embargo, because the author’s declaration takes precedence. RRS is the tool that keeps zero-embargo green deposit available even in journals with no proactive compliant route.
How does green compare with gold and hybrid (APC) routes?
Gold open access means publishing directly in a fully open access journal or platform, where the article is freely available from the publisher at the point of publication — usually funded by an APC, which cOAlition S members will financially support. Hybrid — publishing open access within an otherwise subscription journal — is explicitly not supported by cOAlition S funding except within pre-approved transformative arrangements.
| Dimension | Green (zero-embargo repository) | Gold / OA journal | Rights Retention Strategy |
|---|---|---|---|
| Where you publish | Any subscription journal | Fully open access journal/platform | Any journal (RRS is a licensing overlay, not a venue choice) |
| Typical cost to author/funder | No APC | APC, funder-supported | No APC |
| Embargo permitted | None | None (immediate by definition) | None |
| Version deposited/published | AAM or VoR, in a repository | VoR, on publisher platform | AAM, in a repository, licensed at submission |
| Licence | CC BY (default) | CC BY (default) | CC BY, asserted before any publisher agreement |
For research-office staff advising authors, the practical guidance is: green zero-embargo deposit is generally the cheapest compliant route, RRS is the safeguard that keeps it available when a publisher resists, and gold/APC remains appropriate where funder policy or discipline norms favour immediate publisher-side open access.
Frequently asked questions
What does green open access mean?
Green open access means self-archiving a copy of a peer-reviewed article in an online repository — institutional, subject-based, or general-purpose — independently of the journal’s own access model. The author retains the ability to publish in any journal, including subscription titles, while separately making a version openly available at no cost to readers.
What is the difference between gold and green open access?
Gold open access means the publisher itself makes the article freely available immediately, typically funded by an APC. Green open access means the author self-archives a copy in a repository, which can apply even when the journal itself remains subscription-based, and normally carries no publication fee.
Is green open access free?
Yes. The green route generally involves no article processing charge to the author, funder, or institution. The only ongoing costs are the repository’s own infrastructure, which is typically funded institutionally rather than per-deposit, making green the lowest-cost Plan S compliance path for most authors.
What is Plan S in open access?
Plan S is an open access policy initiative launched by cOAlition S in September 2018, requiring that scholarly publications from research funded by its members be made immediately and openly available, with effect from 2021, via open access journals, platforms, or zero-embargo repository deposit.
What this means for research offices
Advising authors correctly requires distinguishing three separate questions: is the venue itself compliant (checked via cOAlition S’s Journal Checker Tool), does the author need Rights Retention to secure deposit rights, and is the target repository actually OpenDOAR-registered and criteria-compliant. Treating these as one question is the most common cause of authors believing they have complied when they have not — and it should be confirmed at submission, not after acceptance, since retrofitting a CC BY declaration onto a signed publisher agreement is frequently unenforceable.
Outlook
cOAlition S committed to a formal review of Plan S’s requirements, including the role of repository-based compliance, with several “strongly recommended” repository criteria (such as JATS XML full text and open citation data) flagged for possible upgrade to mandatory status. Research offices should expect repository technical requirements to tighten rather than relax, making early alignment with OpenDOAR criteria and RRS-based submission workflows a durable investment. For institutions building broader compliance workflows, see CASRAI’s research administration resources.
