U.S. General Services Administration gsa.gov per diem FAQs incidental expenses Frequently Asked Questions, Per Diem GSA GSA per diem FAQ government http://www.gsa.gov/portal/content/104208#17 gsa.gov GSA GSA incidental expenses U.S. General Services Administration "Frequently Asked Questions, Per Diem", GSA GSA: Per Diem FAQs "Frequently Asked Questions, Per Diem", GSA incidental expenses Per Diem Rates GSA per diem FAQ http://www.gsa.gov/portal/content/104208#11