Federal Government employment data, full-time and part-time, are compiled by the Bureau of the Census from data collected by the U.S. Office of Personnel Management (OPM) in two separate surveys. Data by governmental function are for October from 1992 through 1995, for March for 1997 to 2002, and for December for 2003 to 2005. These data are based on the Monthly Report of Federal Civilian Employment (Standard Form 113A).

Employee counts are the on-board "head count" as of the end of the reporting period. The data collected for this survey capture all Federal civilian employees, including seasonal and intermittent employees, and employees on foreign assignments residing outside the 50 states and the District of Columbia. Employees of the Central Intelligence Agency, the National Security Agency, and the Defense Intelligence Agency are not included in any of the data presented by government function. Federal judges, members of Congress and their staffs, employees of the Congressional Budget Office, and elected (with the exception of the President) and appointed officials of the Executive Branch are included. Employees of non-appropriated funds of defense activities are not classified as Federal employees; therefore, they are excluded from both OPM surveys.

Three functions apply only to the Federal Government and have no counterpart at the state and local government levels: national defense and international relations, postal service, and space research and technology.

The payroll data are a total monthly payroll only. There is no detail available for full-time or part-time employee payrolls.

Federal employment data by state are collected biennially in even-numbered years as of December 31st of the survey year. These data include total employment counts only. There is no detail for full-time employment, part-time employment or payrolls. Excluded from the data are seasonal and intermittent employees; employees on foreign assignments residing outside the 50 states and the District of Columbia; and employees of the Public Health Service's Commissioned Corps, the Central Intelligence Agency, the National Security Agency, and the Defense Intelligence Agency.

Included in the total count of Federal employees by state, but not allocated by state, are: Federal judges and other employees of the Federal Courts; and employees of the Department of Justice's Federal Bureau of Investigation who are employed outside the District of Columbia. Members of Congress and their staffs, employees of the Congressional Budget Office, and elected officials with the exception of the President) and appointed officials of the Executive Branch working in the District of Columbia are included in employee counts for the District of Columbia.