Since 2011, the National Science Foundation (NSF) has required that all grant proposals include a Data Management Plan describing how the proposal will conform to NSF policies on the dissemination and sharing of research results. Proposals that do not include a Data Management Plan cannot be submitted through the Grants.gov proposal submission interface.
NSF has published its requirements for Public Access to results of NSF-funded Research. In addition, in March 2017 NSF updated its Frequently Asked Questions (FAQs) for Public Access .
From the NSF's current Dissemination and Sharing of Research Results:
Investigators are expected to share with other researchers, at no more than incremental cost and within a reasonable time, the primary data, samples, physical collections and other supporting materials created or gathered in the course of work under NSF grants. Grantees are expected to encourage and facilitate such sharing. See Award & Administration Guide (AAG) Chapter VI.D.4.
Proposals submitted or due on or after January 18, 2011, must include a supplementary document of no more than two pages labeled “Data Management Plan”. This supplementary document should describe how the proposal will conform to NSF policy on the dissemination and sharing of research results. See Grant Proposal Guide (GPG) Chapter II.C.2.j for full policy implementation.
Key elements of an NSF Data Management Plan include:
Other relevant information from NSF:
Unidata has a sample Data Management Plan for an NSF proposal here.