Plan S and Diamond OA: where the open-access…

Seven years after Plan S was announced and five years after its 2021 implementation deadline, the open-access conversation in 2026 looks meaningfully different from what its architects expected. The APC-plus-Read-and-Publish trajectory that dominated 2019-2023 is now competing with a much louder Diamond OA movement, with Subscribe-to-Open playing a quiet but important supporting role, and with sharp critique of the inequity that APC-based OA has reinforced. This post walks through the current state of the conversation and what we expect to see settle by 2027.

Plan S compliance in 2026

Plan S, the policy framework launched by cOAlition S in 2018, required that recipients of cOAlition S funder grants make their resulting publications immediately open access under a CC BY licence, via one of three routes: publication in a fully OA journal, publication in a hybrid journal under a transformative agreement, or self-archiving in a repository (the green route) without embargo and with retained rights.

By 2026 the picture is mixed but not in the directions originally feared. Compliance among cOAlition S funder grantees is high (above 90% in the most recent monitoring report) but the modal route is no longer transformative agreements; it is rights-retention deposit. The Rights Retention Strategy, in which authors apply a CC BY licence to the accepted manuscript regardless of journal policy, has been quietly successful. By 2026 most major publishers have either explicitly accommodated RRS or stopped fighting it.

The transformative-agreements track did not transform the publishing economy as cOAlition S had hoped. Read-and-Publish deals at the consortium and country level moved a lot of money from subscriptions to APCs but did not significantly change the underlying cost or the publisher consolidation. The funder-led price transparency requirement (Plan S has required publishers to disclose service-based pricing for some years now) has produced data but not yet pressure.

The Diamond OA inflection

The biggest shift in 2024-2025 was the move of significant funder attention from APC-based Gold OA to Diamond OA: journals that charge neither authors nor readers, funded instead by institutions, learned societies, libraries, and consortia. The 2023 Action Plan for Diamond Open Access from Science Europe, cOAlition S, OPERAS, and the French ANR, followed by the 2024 launch of the Diamond Open Access Capacity Centre, materially changed the funding landscape for community-led journals.

By 2026 the visible result is a wave of new and renewed Diamond OA journals, particularly in the humanities and social sciences where APCs have always sat uncomfortably with the discipline’s economics. The OPERAS DOAB and DOAJ now flag Diamond OA journals explicitly. The 2024 Plan Diamond joint declaration committed signatory funders and institutions to channelling a defined fraction of OA-related spending into Diamond OA infrastructure.

The structural challenge for Diamond OA remains sustainability. A journal funded by a single consortium is one budget cycle away from disappearing. The current direction is to pool funding across consortia and to professionalise the support layer (production, hosting, copy-editing, indexing) rather than reinventing it per journal.

Subscribe-to-Open deserves more attention than it receives. The S2O model, pioneered by Annual Reviews and now adopted by EDP Sciences, Berghahn, and a growing list of others, asks the existing subscribers to continue paying their subscriptions; if enough do, the journal flips to open access for that year. If the threshold is not met, the journal stays subscription. The mechanism preserves a sustainable revenue model while flipping content to OA without APCs.

S2O has been remarkably durable. Annual Reviews has hit the threshold every year of the programme; Berghahn flipped over thirty journals to S2O across humanities and social sciences. The model is constrained: it works for journals with a substantial existing institutional subscriber base, less well for new journals or for those without an institutional market. But where it fits, it works, and it sidesteps the APC-inequity problem entirely.

Read-and-Publish agreements: the messy middle

Read-and-Publish (also called Transformative Agreements) bundle subscription access and APC publishing into a single contract between a library consortium and a publisher. They peaked in deal-volume around 2022-2023 and have plateaued since.

The criticisms have sharpened. R&P deals concentrated OA publishing capacity in well-resourced consortia (Germany’s Project DEAL, the UK’s JISC deals, the Dutch and Swedish consortia). Authors at unsupported institutions, particularly outside the wealthy world, faced full APCs while their better-resourced peers published OA “for free” under their consortium’s deal. The result was an inequity that the OA movement explicitly set out to remove and instead repackaged.

cOAlition S’s commissioned review in 2023 concluded that transformative agreements had not produced the cost decrease that would justify their continued central role and recommended a transition away from them. By 2026 several major consortia are renegotiating R&P deals into a hybrid of capped APC pools, fee waivers for unaffiliated authors, and Diamond OA investments. The direction of travel is clear; the speed is slow.

The equity reframing

The phrase bibliodiversity entered the open-access conversation in 2018 via the Jussieu Call and has steadily gained traction since. It captures something the Plan S framing missed: openness alone does not address the dominance of English-language, Global-North-headquartered, APC-funded publishing. A genuinely equitable scholarly communication system needs multiple languages, multiple regional infrastructures, and multiple economic models, not just open access to the existing system.

The 2024 UNESCO Recommendation on Open Science, and the 2024-2025 work by the cOAlition S successor strategy group on “equity in scholarly communication,” both center bibliodiversity. The practical translation is that funders are increasingly willing to count regional-language publication, Diamond OA, and community-led infrastructure as legitimate research outputs, not as second-tier venues.

The push intersects with responsible assessment: as long as assessment privileges high-impact English-language journals, no amount of OA policy will rebalance global publishing. DORA, CoARA, and the Hong Kong Principles all argue for that broader reform, but the mechanics of changing institutional promotion and tenure committees lag the policy by years.

Where the global South is going

SciELO (Latin America), AJOL (Africa), J-STAGE (Japan), and similar regional infrastructures are the underacknowledged backbone of global Diamond OA. They have operated for decades on a model that flagship Plan S signatories are belatedly endorsing. The 2024-2025 conversation has shifted from “how do we bring Global South authors to Global North journals” to “how do we recognise and resource the regional infrastructures that already publish them.” cOAlition S has begun direct funding agreements with several regional infrastructures.

The peer-review and quality-assurance question that historically dogged regional infrastructures has not gone away, but it has changed shape. AJOL and SciELO have invested heavily in DOAJ-aligned editorial practice; the data show their journals’ peer-review rigour comparable to similarly-scoped Global North journals. The reputational gap that remains is mostly a function of bibliometric assessment patterns, not editorial quality.

What’s coming in 2026-2027

Three things to watch. First, the second wave of Plan S: cOAlition S has signalled that its next-phase strategy (drafted through 2025, expected in mid-2026) will pivot toward Diamond OA, equity, and the de-prioritisation of transformative agreements. Second, institutional re-investment: as R&P deals expire, libraries are increasingly redirecting their formerly subscription budgets into open infrastructure (Diamond OA, preprint servers, institutional repositories). The MIT Framework and similar institutional principles are influential here. Third, cross-funder coordination: the gap between cOAlition S funders and the major North American funders (NIH, NSF, the Tri-Agencies in Canada) has narrowed; OSTP’s 2022 memo and its 2026 implementation are pushing the US system in a similar direction, though through different mechanisms.

For authors, the practical advice is unchanged: deposit your accepted manuscript in your institutional repository under a CC BY licence using the rights-retention model; choose Diamond OA where it exists and serves your community; choose Gold OA in journals with transparent pricing where it does not; resist the assumption that the journal-impact-factor ladder is the path to a sustainable career.

References

cOAlition S, Plan S Principles and Implementation Guidance (2018, revised 2020). Science Europe, cOAlition S, OPERAS, ANR, Action Plan for Diamond Open Access (2023). Jussieu Call for Open Science and Bibliodiversity (2018). UNESCO, Recommendation on Open Science (2021, with 2024 implementation report). Suber, Open Access (MIT Press, revised 2024).