NSF Provides Guidance on Unfunded Collaborations
Except in limited cases, the National Science Foundation (NSF) prohibits voluntary committed cost sharing in proposals. However, proposers may include voluntary uncommitted cost sharing.
Voluntary uncommitted cost sharing must not be included in the budget or budget justification. Instead, any substantial collaboration with individuals not included in the budget should be described in the Facilities, Equipment and Other Resources section of the proposal and documented in a letter of collaboration from each collaborator.
For more information about unfunded collaborations, see the November/December 2017 issue of the NSF Proposal & Award Policy Newsletter.