Publisher versions of journal articles are deposited directly by the journal or publisher to PMC; no author action is required to do so. Journals with an active agreement to deposit all articles can be found in the PMC Journal List. As some journals included in the PMC Journal List may embargo public availability of articles, review the specific record associated with the journal of interest to confirm it has a Release Delay of 0 months (Immediate release) that meets Policy requirements and an Agreement Status of Active. Otherwise, you may need to make special arrangements with the journal to remove the embargo on a given article or submit the Accepted Author Manuscript to NIHMS.

Selective Deposit is a PMC participation option intended for the deposit of a subset of articles from a collection of journals. This model is generally used by publishers who offer a hybrid publishing model, i.e., subscription-based journals in which selected open access articles are published, or publishers who wish to support the policies of a particular funder which require articles to be made available in PMC under specific license terms.

If neither of the above deposit options apply, you may deposit your author accepted manuscript to one of two manuscript submission systems to comply with a designated funder policy:
NIH Manuscript Submission System
Europe PMC