OPM (Office of Personnel Management)
The federal agency that publishes the official pay-period calendar and federal holiday observance schedule.
The U.S. Office of Personnel Management (OPM) is the federal agency that administers human resources policy for the federal civilian workforce, including the official federal pay-period calendar and federal holiday observance schedule. Most U.S. payroll providers, PEOs, and federal contractors anchor their biweekly schedules to the OPM convention — pay period 1 of any year begins on the first Sunday on or before January 1 — so adopting the OPM anchor in your own business produces a calendar that matches every other system that touches your payroll.
OPM does not make law on private-sector payroll cadence; that's controlled by state wage payment statutes and the FLSA. But OPM's published pay-period calendar functions as a de facto standard for the U.S. small-business payroll ecosystem, and the schedules on this site follow it without exception for biweekly schedules.