- What is the Budapest Open Access Initiative?
- What is Plan S?
- BOAI vs Plan S: a side-by-side comparison
- Key differences explained
- Common questions, answered
- What this means for institutions, researchers and publishers
- Two blueprints, one destination
The Budapest Open Access Initiative (BOAI) and Plan S are the two documents most frequently invoked when someone asks “what does open access actually require?” — yet they answer that question in almost opposite ways. BOAI is a voluntary declaration of principle from 2002; Plan S is a binding funder mandate from 2018. Readers arriving from searches around cOAlition S often want to know which framework applies to their situation, and why the two differ so sharply in enforceability. This piece sets out both, side by side, with the dates, mechanisms and licensing terms that distinguish them.
What is the Budapest Open Access Initiative?
BOAI arose from a small meeting the Open Society Institute convened in Budapest on 1-2 December 2001, and the resulting statement was released publicly on 14 February 2002. It was funded by a US $3 million grant from the Open Society Institute and signed initially by 16 individuals, including Peter Suber, Stevan Harnad, Michael Eisen and Jean-Claude Guédon — figures who went on to shape the wider open access movement.
The declaration gave one of the first widely used definitions of open access: free availability on the public internet, permitting any user to read, download, copy, distribute, print, search, link to, or text-mine the full text, with the only constraint being authors’ right to control the integrity of their work and be properly credited.
- Green open access: authors self-archive a copy of their peer-reviewed paper in an open repository.
- Gold open access: journals publish articles openly from the outset, funded by means other than reader subscriptions.
BOAI does not mandate either route, set a deadline, or monitor compliance. Its 10th-anniversary statement (2012) added a recommendation for CC BY licensing and repository infrastructure; its 20th-anniversary update (BOAI20, 2022) issued four high-level recommendations for the next decade. By 2023, over 6,800 individuals and 1,600 organisations had signed it. Alongside the 2003 Berlin Declaration and Bethesda Statement, BOAI is one of the three founding texts of the open access movement.
What is Plan S?
Plan S was launched in September 2018 by cOAlition S, a group of national and international research funders including UKRI, several European research councils, and the European Commission. Unlike BOAI, Plan S is a mandate: it requires that, for research funded from 2021 onwards, resulting peer-reviewed publications must be made immediately open access — in a compliant journal, on a compliant platform, or via an open repository — with no embargo.
Plan S sets out ten principles covering licensing, author rights and cost transparency. Its most consequential requirements are:
- Open licensing — publications must carry an open licence, preferably CC BY.
- Rights retention — authors or their institutions retain copyright rather than transferring it to the publisher.
- No pure hybrid support — cOAlition S will not fund publication in subscription journals that offer paid open access options, except within time-limited transformative agreements.
- Fee transparency — where article processing charges apply, they must be disclosed and justified.
Because Plan S is tied to funding conditions, compliance is checked, and non-compliant publications can put a researcher’s funding eligibility at risk — a mechanism BOAI simply has no equivalent of.
BOAI vs Plan S: a side-by-side comparison
| Feature | Budapest Open Access Initiative (BOAI) | Plan S |
|---|---|---|
| Launched | 14 February 2002 | 4 September 2018 |
| Originator | Open Society Institute-convened group of individuals | cOAlition S (national/international research funders) |
| Nature | Voluntary declaration of principle | Binding funder mandate |
| Enforcement | None — moral/advocacy suasion only | Tied to grant funding conditions |
| Preferred routes | Green (self-archiving) and gold (OA journals) | Compliant journal, platform, or repository, no embargo |
| Licensing | Not prescribed (CC BY recommended from 2012) | Open licence required, CC BY preferred |
| Implementation deadline | None set | Applied to research funded from 2021 |
Key differences explained
The clearest way to read the two documents is as different stages of the same movement. BOAI supplied the definition and the philosophical case for open access; Plan S supplied a compliance mechanism to accelerate uptake once voluntary adoption plateaued. Two decades on from BOAI, much subscription-journal literature remained closed, which is precisely the gap cOAlition S funders set out to close by attaching conditions to their money rather than relying on persuasion.
A second difference is scope. BOAI addresses the entire scholarly community — researchers, institutions, publishers, governments — as a universal statement. Plan S applies specifically to researchers funded by cOAlition S members, so its reach is defined by funder membership rather than by field or geography.
Common questions, answered
What is the Budapest Open Access Initiative concerned with?
The Budapest Open Access Initiative is concerned with making peer-reviewed research literature freely available online, without financial or legal barriers, so anyone can read, download, copy, distribute, or text-mine it, subject only to authors’ right to be properly acknowledged.
What is the history of BOAI?
BOAI emerged from a meeting the Open Society Institute convened in Budapest on 1-2 December 2001, was released publicly on 14 February 2002, and was followed by 10th-anniversary (2012) and 20th-anniversary (2022) recommendation updates.
In which year did the Budapest Open Access Initiative Declaration take place?
The Budapest meeting took place in December 2001, and the resulting declaration was formally released to the public on 14 February 2002, making it one of the founding texts of the open access movement.
What is the difference between BOAI and Plan S?
BOAI is a voluntary statement of principle with no enforcement mechanism, while Plan S is a binding funder mandate from cOAlition S requiring immediate open access, specific licensing, and compliance monitoring for funded outputs.
What this means for institutions, researchers and publishers
For research administrators, the practical takeaway is that BOAI and Plan S sit at different points of an institutional compliance stack. BOAI-aligned green open access — depositing a copy in an institutional or subject repository — remains a low-cost baseline that satisfies neither Plan S’s no-embargo rule nor its licensing requirement on its own, but supports discoverability and long-term preservation regardless of funder.
Publishers navigating both frameworks typically need:
- A CC BY (or equivalent open) licensing option at the article level.
- A rights-retention pathway that does not require copyright transfer.
- Transparent, itemised article processing charges where fees apply.
- Repository-compatible metadata so green deposits can satisfy funder checks.
Institutions should treat BOAI’s language as the shared vocabulary of open access policy — it is what most local and national OA policies still cite when defining terms — while treating Plan S (and successor funder mandates modelled on it) as the specific compliance checklist that determines whether a given grant-funded output is audit-ready.
Two blueprints, one destination
BOAI and Plan S are not competitors; they are sequential milestones in the same movement toward open scholarly communication. BOAI defined what open access means and why it matters; Plan S demonstrated what happens when funders convert that definition into a binding condition of grant compliance. Institutions that understand both — the founding principles and the enforcement mechanism layered on top — are better placed to build policies that satisfy funder mandates without losing sight of the broader access mission BOAI first articulated in 2002.
Research-administration teams working across CRediT contributor roles, authorship policy, and funder compliance can find related terminology in the CASRAI Dictionary and further context in the research administration pillar.
