The United States Code and the Code of Federal Regulations are the basis of agency policies and regulations pertaining to compensation.
From time to time, the Office of Personnel Management (OPM) releases Compensation Policy Memos that provide details about timely pay issues. OPM also releases Emergency Memos regarding pay issues in time of natural disasters or emergencies.
Both the Department of Defense and the Department of the Navy issue pay policy memos that give additional guidance, clarification, and useful examples.