As referenced in Article 8, Sections 4 and 5, of the USPS-NALC and USPS-APWU national agreements, the December period (during which penalty overtime regulations are not applicable) consists of 4 consecutive service weeks.

This year, the December period begins Pay Period 26–21, Week 1 (December 4, 2021) and ends Pay Period 01-22, Week 2 (December 31, 2021).

— Labor Relations Policies and Programs,
Labor Relations, 10-7-21

Source: USPS