Plan S principles remain fully in force in 2026: none of the original ten clauses has been formally withdrawn. What has changed is enforcement — the temporary carve-out for hybrid “transformative agreements” expired after 2024, and cOAlition S’s November 2025 Strategy for 2026-2030 now commits to rewriting the principles document itself for the first time since 2019.
Plan S is the funder-driven open access mandate launched by cOAlition S on 4 September 2018, requiring that scholarly publications arising from participating funders’ grants be published immediately, without embargo, in compliant open access journals, platforms or repositories. This article works through each of the ten original principles in turn and states, clause by clause, what is still mandatory, what has been reinterpreted, and what has actually lapsed.
- What are the ten original principles of Plan S?
- Which principles are still mandatory in 2026?
- Which principles have been relaxed, tightened or left unresolved?
- Answer-first Q&A on Plan S in 2026
- Implications and outlook for institutions and publishers
What Are the Ten Original Principles of Plan S?
cOAlition S describes Plan S as “one target and 10 principles.” The target is the immediate, embargo-free open access requirement; the ten principles, published in the 2019 Plan S Principles and Implementation guidance, set out how that target is delivered and governed.
- Authors or their institutions retain copyright, under an open licence — preferably CC BY — consistent with the Berlin Declaration.
- Funders develop robust criteria and requirements for compliant open access journals, platforms and repositories.
- Funders coordinate to establish and support compliant venues and infrastructure where none yet exist.
- Open access publication fees are covered by funders or institutions, never by individual researchers.
- Funders support a diversity of business models, with fees kept transparent, proportionate and capped where applied.
- Funders encourage governments, universities, libraries, academies and learned societies to align their own policies.
- Monographs and book chapters follow a longer, separately negotiated timeline.
- Funders do not support the “hybrid” subscription-plus-OA model, except transitionally through time-limited transformative arrangements.
- Funders monitor compliance and sanction non-compliant grantees.
- Funding and assessment decisions value the intrinsic merit of research outputs, not the journal, its impact factor, or the publisher.
Which Plan S Principles Are Still Mandatory in 2026?
Seven of the ten principles are unchanged and enforced exactly as written in 2019. Copyright retention, the requirement that funders (not authors) pay compliant fees, compliance monitoring and sanctions, and merit-based assessment of outputs rather than journal metrics all remain live obligations for cOAlition S’s 28 member funders — up from the twelve founding organisations in 2018, and now spanning agencies in Europe, North America, Jordan, Zambia, South Africa and Australia, per cOAlition S’s own Strategy 2026-2030 document.
The Journal Checker Tool still operationalises the “robust criteria for compliant venues” principle for every submission, and the longer, separate timeline conceded for monographs and book chapters in 2019 remains unresolved and unchanged in 2026 — cOAlition S has not published a revised monographs timetable.
Which Principles Have Been Relaxed, Tightened or Left Unresolved?
No principle has been deleted outright. Two have shifted, and in the opposite direction to what is commonly assumed: the anti-hybrid clause has tightened, not loosened, and the fee-diversity clause has been reinterpreted toward non-APC models rather than relaxed.
| Principle | 2019 wording (summary) | 2026 status |
|---|---|---|
| Copyright & CC BY | Authors retain copyright; CC BY preferred | Mandatory, unchanged |
| Robust venue criteria | Funders set criteria for compliant OA venues | Mandatory; enforced via Journal Checker Tool |
| Infrastructure support | Funders coordinate to build missing OA venues | Mandatory, strengthened (Strategic Priority 2) |
| Funder-paid fees | Fees paid by funders/institutions, not researchers | Mandatory, unchanged |
| Fee diversity & transparency | Diverse business models; transparent, capped fees | Reinterpreted toward diamond OA and PRC models |
| Policy alignment | Funders encourage institutional alignment | Mandatory, unchanged |
| Monographs timeline | Longer, separate process for books | Unresolved; no 2026 update published |
| No hybrid model | Hybrid banned, except transitional arrangements | Tightened: transitional carve-out expired after 2024 |
| Monitoring & sanctions | Funders monitor and sanction non-compliance | Mandatory, unchanged |
| Merit-based assessment | Assess outputs, not journal metrics | Mandatory, strengthened via assessment-reform links |
The “no hybrid model” principle is the clearest case of change, and it runs counter to a common misreading. cOAlition S confirmed on 26 January 2023 that financial support for open access publishing under transformative arrangements — the negotiated pathway that let hybrid journals count as compliant during a transition period — would end after 2024, with Transformative Journal support ceasing on the same date and no new applications accepted. That decision followed 2023 compliance reviews showing roughly two-thirds of registered Transformative Journals were not meeting their agreed open access growth trajectories. This closure predates and is separate from the newer 2026-2030 strategy; it is not a relaxation but the expiry of a deliberately time-limited exception, which makes the underlying anti-hybrid principle stricter in practice from 2025 onward.
The fee-diversity principle has not been dropped either. Instead, the cOAlition S Strategy for 2026-2030, published 12 November 2025, commits under Strategic Priority 1 to “review and update the Plan S principles and implementation guides, including enhancing the focus on sustainable and equitable models, such as PRC, diamond open access and preprints.” Diamond open access refers to publishing venues that charge neither authors nor readers; PRC (“Publish, Review, Curate”) describes models — pioneered by platforms such as eLife — where papers are posted openly before formal peer review, then reviewed and curated in the open. Neither model existed at meaningful scale when the original fee-transparency principle was drafted in 2019.
Answer-First Q&A on Plan S in 2026
What are the 10 principles of Plan S?
The ten principles cover copyright retention with CC BY licensing, funder-set venue criteria, infrastructure support, funder-paid fees, diverse and transparent fee models, policy alignment across institutions, a separate monographs timeline, a ban on hybrid publishing (except time-limited transitional arrangements), compliance monitoring with sanctions, and merit-based research assessment.
Is Plan S still in effect in 2026?
Yes. Plan S remains active and binding for cOAlition S’s 28 member funders, and the coalition’s Strategy 2026-2030, published November 2025, reaffirms the objective of full and immediate open access while committing to update — not abandon — the underlying principles document.
What happened to Plan S’s transformative agreements?
cOAlition S ended financial support for open access publishing under transformative arrangements, including Transformative Journals, after 2024, following a 26 January 2023 announcement. The transitional exception that let some hybrid venues count as compliant has therefore expired, tightening enforcement of the original anti-hybrid principle.
What is diamond open access under Plan S?
Diamond open access describes journals and platforms that charge no fees to either authors or readers. cOAlition S’s 2026-2030 strategy names diamond OA, alongside PRC models and preprints, as a priority area for its updated principles and implementation guidance.
Implications and Outlook for Institutions and Publishers
For research administration teams, the practical compliance checklist is largely stable: continue verifying venues through the Journal Checker Tool, ensure CC BY licensing and funder-paid fees are documented, and treat any residual “transformative agreement” listing as expired rather than compliant. Publishers still running hybrid titles without a diamond OA or PRC pathway face reduced routes to Plan S compliance now that the transitional carve-out has closed.
The material open question for 2026-2027 is not whether Plan S survives, but how its updated principles document — due under Strategic Priority 1 of the 2026-2030 strategy — redefines “diverse business models” once diamond OA and PRC are formally written in. cOAlition S has structured its strategy in two phases, an initial 2026-2027 period followed by 2028-2030 priorities subject to Leaders Group review, so institutions should expect incremental guidance updates rather than a single rewrite. An independent study commissioned by cOAlition S, Galvanising the Open Access Community: A Study on the Impact of Plan S (Zenodo, DOI 10.5281/zenodo.13738479), credits the coalition with raising the profile of open access and bringing publishers to the negotiating table — the same leverage it is now applying to push the next generation of non-APC models.