Elsevier open-access fee waived for subscribers?

@Stephan Kolassa has given the technically correct answer. I will add that all of this is irrelevant to the vast majority of universities, since they don't pay individual journal prices. They pay for an Elsevier bundle, and Elsevier forces them to keep the amount paid secret. It seems clear that bundle prices are determined based on what Elsevier believes a university can afford (i.e., will submit to) and are not based on any formula involving numbers of articles. Thus Elsevier is double-dipping. The only way they could prove otherwise would be to have a transparent pricing scheme and to allow universities to make public the actual prices paid.

Note that Elsevier has gone far beyond this and even charged for access to articles whose authors paid an OA fee in some cases.

Stephan is entirely correct: the OA APCs Elsevier charge are not directly dependent on whether or not you are a subscriber. The method used by Elsevier, and most publishers, is to reduce the overall subscription cost in proportion to the number of OA articles in a journal, not reduce the APCs in proportion to subscription spending. In theory, were a hybrid journal to go 50% OA, then the subscription price would be halved - which makes sense - but as David notes, the mechanics of this are pretty opaque. Most journals are not bought at list price, and things like varying numbers of articles year-on-year confuse things.

That said, there are projects which run the way you envisage it working - where APCs are reduced or waived for subscribers. The recent UK initiative to put substantial government funds into gold OA has led to a lot of pressure to come up with a system like this, because otherwise we would create a situation where UK universities spent very heavily on gold OA but only saw small reductions in the global subscription rates. Similar systems are being set up in Austria and elsewhere, and I suspect will become common over the next few years.

At the moment, two of the major publishers (Taylor & Francis and Wiley) offer such "offsetting" schemes. The T&F one is summarised here and the Wiley one here. With these, the subscribing institution gets a "rebate" voucher based on their subscription (or subscription + APC) spend over the previous year.

They can then use this to pay for future APCs. Elsevier do not have such a system, but JISC are strongly pushing major hybrid publishers to set them up, and I feel it's likely we'll see one for Elsevier within the next couple of years.

Edit: the RCUK Open Access Review, released today (26/3), has a little more detail (Appendix H) on the current offsetting projects - as well as T&F and Wiley, there are active projects from the Institute of Physics, the Royal Society of Chemistry, and Sage. The Sage one works exactly as the original post assumed - authors at subscribing institutions are charged a heavily discounted APC - while the others are a rebate/voucher system based on total spend.

Edit2: and as of 31/3, Springer have announced a very vague offsetting plan with JISC. No details on how it works yet but probably some kind of voucher system.

In the help page you link to, there are three relevant subheadings:

For journals that publish only subscription articles

(snip)

For journals that publish only open access articles

(snip)

For journals that publish both subscription articles and open access articles:

Adjustments in individual journal subscription list prices are made in the same way as for journals that publish only subscription articles. We do not count open access articles when setting subscription prices for titles. Subscription prices are therefore not affected by the volume of open access articles published in the journal.

Adjustments in article publishing fees (APCs) are made in the same way as for articles that are published in journals that publish only open access articles. We do not count subscription articles when setting APC prices for articles. APC prices are therefore not affected by the volume of subscription articles published in the journal.

The first two sections explain how Elsevier set subscription prices for subscription-only (no OA) journals, and publication fees for OA-only journals.

The third section, on mixed OA/non-OA journals, refers to the previous two and explains

• How subscription prices are set, taking OA articles into account (they are not counted in the calculation according to the first section)
• How OA publication fees are set, taking subscriptions into account (they are not counted in the calculation according to the second section)

Bottom line: the idea is not that you get a waiver for your subscription based on how many OA articles you (or your school) has published in the journal. Nor is it that you get a reduced OA publication fee based on subscribing to the journal (yourself or through your school).

Rather, everything is lumped together. It's simply a mixed calculation.