Open access has a simple, compelling promise: research that anyone can read, free of paywalls, wherever they are. But removing the charge to readers does not remove the cost of publishing. Editorial management, peer-review coordination, production, hosting and preservation all cost money, and that money has to come from somewhere. The question of who pays, and how for open access has become one of the most consequential and contested issues in scholarly communication — consequential because it determines who gets to publish, and contested because the wrong model can simply move the barrier from readers to authors. This article surveys the main ways open-access publishing is paid for, drawing on the funding and finance domain of the CASRAI Dictionary. For the underlying concepts, our explainer on what open access is sets the scene.
Article processing charges
The most familiar mechanism is the article processing charge, or APC: a fee paid, usually by the author or their institution or funder, when an article is accepted, in exchange for making it openly available. The APC model neatly inverts the subscription model — instead of readers paying to read, the publishing side pays to publish, and the work is then free to all. Its appeal is that it provides a clear revenue stream while keeping the literature open. But the APC model carries a serious equity risk that has shaped the entire debate: if the ability to publish depends on the ability to pay a fee, then researchers without funding to cover APCs — early-career researchers, those at less wealthy institutions, those in lower-income countries, those in disciplines with little grant money — can find themselves shut out. Open to read can quietly become closed to publish. Much of the policy and financial machinery around open access exists precisely to manage this risk.
Transformative agreements
One major response is the transformative agreement, often structured as a read-and-publish (or publish-and-read) deal. These are agreements, typically negotiated between publishers and library consortia or national bodies, that bundle together the cost of reading a publisher’s content and the cost of publishing open access in it under a single contract. The idea is to repurpose the money institutions already spend on subscriptions, shifting it towards open-access publishing and away from paywalls — transforming the financial relationship rather than simply adding APC costs on top of existing subscriptions. For an author at a covered institution, the practical effect is that they can publish open access without facing an individual APC, because the cost has been handled centrally. The word transformative signals the intent: these agreements are meant to be a transition, moving the system towards open access rather than a permanent destination. Whether they deliver on that promise — or entrench incumbent publishers at high cost — is exactly what makes them contested.
Funder block grants
A third mechanism addresses the funding gap more directly: the block grant. Rather than expecting each grant to absorb publication costs unpredictably, some funders provide institutions with a dedicated pool of money — a block grant — specifically to cover open-access costs such as APCs. The institution then administers the fund, paying charges on behalf of its researchers. The advantage is that researchers are not left to find publication money from project budgets that may not stretch to it, and the institution gains a degree of oversight over how open-access spending is managed. Block grants are an acknowledgement that if funders require open access, they bear some responsibility for making it affordable — that a mandate without a means is an unfunded burden.
Plan S and the policy backdrop
These financial mechanisms did not arise in a vacuum; they were shaped by funder policy, and above all by Plan S, the initiative through which a coalition of research funders required that research they fund be made openly available. Plan S sharpened the question of payment because it made open access a condition of funding rather than an option, which meant the costs had to be met somehow. It also engaged directly with the equity problem: it has been concerned with caps and transparency on charges, with the terms of transformative agreements, and with ensuring that the drive to open access does not simply create a pay-to-publish system. The policy and the financial mechanisms are inseparable — the policy creates the requirement, and APCs, transformative agreements and block grants are the means by which that requirement is met in practice.
The equity question runs through everything
The thread connecting all of these mechanisms is equity. Each model is, in part, an attempt to answer the same worry: how to make research open to read without making it closed to publish for anyone who lacks money. APCs raise the worry most directly; transformative agreements try to manage it by handling costs centrally; block grants try to ensure the money exists; and Plan S tries to set rules that keep the system fair. The persistence of the worry across every model is a reminder that the goal of open access is not merely free reading but a genuinely more open and equitable scholarly system — and that financial design is where that aspiration is won or lost. Routes such as diamond open access, which charges neither readers nor authors, sit alongside these as part of the wider landscape.
Tracking the money consistently
Managing open-access funding well requires being able to track it: which charges were paid, from which fund, under which agreement, for which output, attached to which grant. For that tracking to work across institutions, funders and publishers, the financial and funding information involved must be described consistently. That consistency is what the CASRAI Dictionary provides: a shared vocabulary so that the funding sources, charges, agreements and acknowledgements flowing through the open-access economy mean the same thing wherever they are recorded. And because publishing is the culmination of contribution, the work behind each output can be described in the same shared framework — the CRediT taxonomy and its full set of contribution roles. Open access changed who can read research; getting the financial models right determines who can take part in producing it.