The Federal agencies expect that “most Federally-funded research programs should have some level of committed faculty (or senior researchers) effort, paid or unpaid by the Federal government. This effort can be provided at any time within the fiscal year (summer months, academic year, or both).” A clarification memo also states that, “… Some types of research programs…do not require committed faculty effort, paid or unpaid by the Federal government ...”
The National Institutes of Health (NIH) Grants Policy Statement notes that “‘zero percent’ effort or 'as needed effort’ is not an acceptable level of involvement for ‘key personnel'."