Open Access Mandate Compliance: What Seven Years of Plan S Data Show

• What Plan S Set Out to Achieve
• The Compliance Data: What Changed Since 2018
• Publisher Pricing and Journal Behaviour
• Common Questions on Open Access Mandates
• What This Means for Institutions and Researchers
• Where Plan S Goes Next

Seven years after cOAlition S launched Plan S in September 2018, the question is no longer whether funder mandates can move the needle on open access mandate compliance — it is what, specifically, moved, and what stayed stuck. cOAlition S’s own monitoring reports, rather than advocacy claims on either side, now give a reasonably clear evidence base for answering that.

What Plan S Set Out to Achieve

Plan S was convened through Science Europe with backing from the European Commission and the European Research Council. Its ten principles required that, from an implementation date eventually set at 1 January 2021 (pushed back a year from the original 2020 target), research funded by signatory organisations be published immediately open access, under an open licence, with no embargo.

The coalition grew to more than two dozen public and philanthropic funders, including UKRI, Wellcome, and — aligned in principle if not formal membership — the Bill & Melinda Gates Foundation. Crucially, Plan S explicitly disfavoured hybrid subscription journals unless covered by a time-limited “transformative arrangement.”

The Compliance Data: What Changed Since 2018

Two mechanisms did most of the practical work. The Rights Retention Strategy, introduced in 2021, lets authors attach a CC BY licence to their accepted manuscript at submission — enabling compliant Green open access regardless of a publisher’s stated embargo. The Journal Checker Tool, launched the same year jointly with Wellcome and UKRI, lets authors verify funder-compliant routes journal by journal before submitting.

According to cOAlition S’s own 2023 Annual Review, around 80% of research outputs from coalition-funded grants were published open access — above the roughly 60% global baseline for research generally. That gap is the strongest single piece of evidence that mandate-plus-tooling outperforms voluntary policy alone.

• Gold OA (immediate, via publisher) became the most-used compliant route.
• Green OA via the Rights Retention Strategy grew as a no-cost alternative.
• Compliance has been consistently stronger in STEM fields than in humanities and social sciences, where funding structures differ.

Publisher Pricing and Journal Behaviour

Publisher behaviour shifted more than pricing transparency did. Transformative agreements — contracts bundling subscription access with open-access publishing rights — proliferated rapidly after 2018, particularly across Europe and North America; by 2024 they were supporting open-access status for well over 300,000 publications, accounting for a substantial share of global gold OA output.

That growth came with a cost concern cOAlition S itself flagged: article processing charges concentrated financial risk on authors and institutions rather than reducing it. In response, cOAlition S announced it would stop funding “transformative journals” specifically after the end of 2024, and co-published an Action Plan for Diamond Open Access with Science Europe and OPERAS to seed no-fee, community-run alternatives.

The unresolved piece is longform outputs. A recent British Academy report found Book Processing Charges from larger publishers typically run £10,000–£20,000 per title, against a UKRI block-grant cap of £10,000 — and that only 18% of book records in UK institutional repositories actually hold the full text. The UK’s own REF 2029 exercise will not mandate open access for monographs this cycle; Research England confirmed in December 2024 it will apply from the following assessment period, from January 2029.

Common Questions on Open Access Mandates

What is an example of an open access initiative?

Plan S is the clearest example: a funder-driven mandate launched by cOAlition S in 2018 requiring immediately open, freely reusable publication of any research these funders finance. Members include UKRI, Wellcome, the European Commission, and national research councils across more than a dozen countries.

Do authors have to pay for open access?

Not necessarily. Plan S’s Rights Retention Strategy lets authors deposit a CC BY-licensed accepted manuscript in a repository at no cost, satisfying compliance without an article processing charge. Gold open access typically requires a publication fee, which is why cost remains the mandate’s most contested feature.

What are the disadvantages of open access?

Critics point to article processing charges shifting costs from readers to authors, disadvantaging researchers at under-resourced institutions and in the Global South. Smaller and society publishers have struggled to compete for transformative agreements, and humanities disciplines have seen slower, patchier compliance than STEM fields.

What exactly does open access mean?

Open access mandate compliance means meeting a funder’s specific publishing requirements — typically an approved licence (usually CC BY), a maximum embargo period, and deposit in a recognised repository or journal. cOAlition S tracks this through annual monitoring reports rather than self-certification alone.

What This Means for Institutions and Researchers

For research administration teams, the practical upshot is that compliance now runs on tooling, not trust: the Journal Checker Tool and Rights Retention Strategy shifted the burden of proof from post-hoc audits to pre-submission checks. That has measurably raised article-level compliance rates without waiting for every journal to convert to full open access.

It has not, however, solved cost equity. Institutions negotiating transformative agreements have effectively subsidised large commercial publishers’ transition, while smaller and society publishers, and now book publishers, face a structurally different cost problem that article-level mechanisms don’t reach. Consulting a shared reference point such as CASRAI’s open research dictionary can help teams keep licensing and embargo terminology consistent across funder policies.

Where Plan S Goes Next

cOAlition S’s 2023 “Towards Responsible Publishing” proposal signalled a pivot away from journal-brand mandates toward funder-supported repositories and article-level open access, still under consultation. Combined with the Diamond Open Access Action Plan and the UK’s REF 2029 timeline for monographs, the next phase of Plan S looks less like a single global rule and more like a set of interoperating, funder-specific mechanisms — a shift that will make monitoring data, not policy text, the real measure of what “compliance” ends up meaning.