Voluntary cost sharing is not expected in federal research proposals and cannot be used as a factor during the merit review. In order for cost sharing to be considered by the funding agency it must be specified in a notice of funding opportunity.
No cost sharing should be budgeted unless it is specifically required by an agency's funding solicitation. If cost sharing is required in the solicitation, it should be included in the proposal budget and should meet other federal requirements for cost-sharing eligibility detailed here.
For more information, contact the Office of Sponsored Programs.