Plan S requirements in 2026 no longer match the ten founding principles cOAlition S published in September 2018 point for point. The rights-retention and price-transparency provisions have hardened into non-negotiable mandates, while the coalition’s tolerance for transitional “transformative” publisher deals has effectively ended — a shift that signals less patience with publisher-led compromise and more direct enforcement of author-side rights.
Plan S requirements are the technical and policy conditions that publications funded by cOAlition S members must satisfy to count as compliant open access. cOAlition S is the international consortium of research funders — including UKRI, Wellcome, the European Commission, and national agencies across Europe and beyond — that launched Plan S on 4 September 2018 to require immediate, licence-free open access to publicly funded research. Eight years on, with the coalition’s 2026-2030 strategy in force, it is worth testing the current rulebook against the original ten principles to see exactly where the mandate has hardened, where it has quietly softened, and what that tells research administrators about cOAlition S’s actual leverage over publishers.
- What has actually changed since 2018?
- Where has the mandate hardened?
- Where has it visibly softened?
- What does this shift signal about coalition leverage?
- Answer-first Q&A
- Implications for institutions and publishers
What has actually changed since 2018?
The founding text set out ten principles, anchored on one non-negotiable clause: from 2021, all publications from cOAlition S-funded research must appear in open access journals, on open access platforms, or in open access repositories, with no embargo. The remaining nine principles covered copyright retention, CC BY licensing, publication-fee funding by funders rather than researchers, price transparency, a phase-out of hybrid journals, and a commitment to judge research on merit rather than journal brand.
By the time of the 2026-2030 cOAlition S strategy, three compliance routes have consolidated: Gold open access (including diamond open access with no author-facing or reader-facing fee), the Rights Retention Strategy applied to subscription-journal submissions, and Green open access via a compliant repository with no embargo. The 2018 principles described intent; the 2026 requirements describe enforcement mechanics.
Where has the mandate hardened?
Two provisions have moved from aspiration to hard gate. Price transparency, only loosely sketched in the 2018 text as a way “to inform the market,” is now an explicit technical requirement under Part III of the Plan S guidance: open access journals and platforms must publish detailed cost and fee-structure data on their own websites, and even fee-free diamond journals must submit price-transparency data to remain listed as compliant.
The Rights Retention Strategy has hardened from a footnote into the coalition’s primary enforcement lever. Authors are now expected to apply a CC BY licence to the accepted manuscript at the point of submission — before a publisher’s licence terms can be negotiated — which lets the author (or their institution) deposit the manuscript immediately, with no embargo, regardless of what the subscription journal’s standard contract says. This converts a principle about “authors retaining copyright” into an operational, author-executed workaround that does not depend on publisher cooperation.
- Mandatory metadata and persistent-identifier requirements (DOI, ORCID, funder ID) that did not exist in the 2018 text are now baseline conditions for any compliant venue.
- APC waiver and discount obligations for authors from low- and lower-middle-income economies, benchmarked against World Bank income classifications, are now mandatory rather than aspirational.
- Repositories must meet a specified 99.7% uptime standard and provide a helpdesk with a one-business-day response commitment — operational detail entirely absent from the founding principles.
Where has it visibly softened?
The clearest retreat concerns transformative agreements. The 2018 principles explicitly rejected the hybrid publishing model but carved out a transitional exception: funders “may contribute to financially supporting” transformative arrangements with a clearly defined timeframe. That exception has now been withdrawn — cOAlition S’s 2026-2030 strategy ends support for transformative agreements as a recognised transitional route, which is a hardening of the hybrid rejection in one sense, but also an acknowledgement that the original transitional bridge failed to deliver a timely full transition and had to be abandoned rather than completed on schedule.
Softer, in practice, is the treatment of monographs and long-form outputs. The 2018 text conceded a longer timeline for books and book chapters “requiring a separate and due process” — and in 2026 that separate process still has not produced binding monograph mandates comparable to the journal-article regime, leaving a persistent compliance gap the original principles anticipated but never closed.
The 2024 review point, flagged in the technical guidance as the moment “strongly recommended” criteria could become mandatory, has also passed without converting most of those criteria — full-text JATS XML availability, OpenAIRE compliance, open citation data under the Initiative for Open Citations — into hard requirements. Those remain recommended, not required, five years after the review date the coalition itself set.
What does this shift signal about coalition leverage?
Reading the hardened and softened provisions together tells a consistent story: cOAlition S has gained leverage over authors and institutions but has arguably lost leverage over publishers. The Rights Retention Strategy and price-transparency rules are enforceable because they route through funder grant conditions and author-executed licensing — mechanisms the coalition controls directly. Ending transformative agreements removes a financial lever it once used to push publishers toward structural change, because those deals required publisher buy-in the coalition could no longer secure or justify funding.
In short, the 2026 requirements have shifted toward parts of the system cOAlition S can compel unilaterally, and away from parts that needed publisher cooperation it could not consistently obtain. That is a rational response to eight years of limited publisher-side reform, but it narrows Plan S’s ambition: the founding principles targeted the publishing market itself; the 2026 requirements increasingly guarantee open access outcomes regardless of whether that market reforms at all.
Answer-first Q&A
What is Plan S in research funding?
Plan S is an initiative launched by cOAlition S on 4 September 2018 requiring that all scholarly publications resulting from research funded by participating funders be made immediately open access, without embargo, via a compliant journal, platform, or repository.
Does Plan S still support transformative agreements?
No. The 2026-2030 cOAlition S strategy ends support for transformative agreements as a recognised transitional compliance route, closing the hybrid-journal exception the 2018 principles had allowed on a temporary, time-limited basis.
What is the Rights Retention Strategy under Plan S?
The Rights Retention Strategy requires funded authors to apply a CC BY licence to their accepted manuscript at submission, letting them deposit it immediately and without embargo in a compliant repository, independent of the publisher’s own licensing terms.
How does diamond open access fit Plan S requirements?
Diamond open access — journals and platforms that charge neither authors nor readers — satisfies the Gold open access compliance route and is explicitly named in the 2026-2030 strategy as a funding priority, provided the venue still submits the required price-transparency data.
Implications for institutions and publishers
Research offices administering cOAlition S grants should treat the widened gap between principle and requirement as a compliance-tracking problem, not a rhetorical one. CC BY at submission, no-embargo deposit, funder metadata, and price-transparency disclosure are now more prescriptive than the 2018 text implied.
| Provision | 2018 principle | 2026 status |
|---|---|---|
| Rights retention | Authors retain copyright, CC BY preferred | Hardened — mandatory CC BY at submission via Rights Retention Strategy |
| Price transparency | Fees “commensurate” and “transparent” | Hardened — explicit disclosure requirement, including for diamond OA |
| Hybrid/transformative journals | Rejected in principle, funded as a transitional exception | Softened/withdrawn — transitional funding exception ended |
| Monographs and books | Longer timeline acknowledged, separate process promised | Softened — separate process still has no binding mandate |
| Metadata, PIDs, repository uptime | Not specified | New — mandatory technical baseline added |
For publishers, the message is that structural leniency has narrowed even as some individual obligations (notably around most “strongly recommended” technical criteria) remain unenforced past their own 2024 review deadline. Institutions should expect cOAlition S to keep tightening author-facing and funder-facing levers first, since those are the ones it can enforce without publisher cooperation.
For research administrators managing funder compliance across multiple mandates, the practical takeaway is to track Rights Retention and repository-deposit obligations as the highest-audit-risk items, since these are where cOAlition S enforcement has visibly hardened rather than drifted. Terminology around open access routes, including diamond and hybrid models, is tracked in the CASRAI Dictionary.
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