According to REF 2021: Overview of open access policy and guidance, institutions can register their institutional repositories with Unpaywall and CORE to harvest metadata to determine compliance with REF 2021:
46. We will assess each HEIs’ overall compliance with the REF 2021 open access policy by:
a. Identifying where more than one, and more than 5%, of in-scope outputs are not compliant with the REF open access policy and are not using an exception. This will be based on the data in the Open access field in the REF2 submission data.
b. Taking a risk-based approach to open access compliance. The risk identification does not itself form part of the audit, but will be used to inform the selection of HEIs and submissions for possible audit review. We will rank6 HEIs by:
i. The number of ‘other’ exceptions used (a higher proportion of ‘other’ exceptions will lead to a higher risk score). Note that use of ‘deposit’, ‘access’ or ‘technical’ exceptions, or the use of the exception for deposit within three months of publication, will not affect the risk score irrespective of how many times these exceptions are used.
ii. Using unpaywall.org to establish whether there is an OA copy of the output (based on the is_oa field).
iii. Using unpaywall.org to establish whether the output is a file with searchable text (based on the url_for_pdf field).
iv. Using Jisc CORE, comparing the datePublished and depositedDate and identifying where the number of days between the two dates is greater than 92. If your institution is using Figshare to host research to be submitted for REF2021, you can register your portal with Unpaywall and CORE for harvesting.
CORE (or IRUS UK and any other aggregators supporting OAI-PMH): Contact email@example.com for your portal’s ListSet URL for OAI-PMH.