Becky,

You've made me do my homework.  A-21 is the source of the "lowest rate to the
feds" rule.  Section D. Direct Costs. 1. General:  "Where an institution
treats a particular type of cost as a direct cost of sponsored agreements, all
costs incurred for the same purpose in like circumstances shall be treated as
direct costs of all activities of the institution".  Also, see Section J.44.
Specialized Service Facilities.  If I'm reading it correctly (whoever knows?),
I believe this section supports the consistency in charging.

Ruth
Office of Research and Sponsored Programs
Lehigh University
Phone: 610-758-3024