Duhaime's Law Dictionary Calendar Quarter Definition: A period of three consecutive months starting on one of January 1, April 1, July 1 or October 1. Related Terms: Calendar Month, Calendar Year, Calendar Day, Calendar Week In Blaschock, quoting from Follett, Justice Craig of the Commonwealth Court of Pennsylvania wrote: "A calendar quarter is one of the four periods of three months each of a calendar year. "A calendar year is the year beginning on January 1 and ending on December 31." REFERENCES: Blaschock v WCAB, 625 A. 2d 194 and at 155 Pa.Cmwlth. 452 (1993) Duhaime, Lloyd, Legal Definition of Calendar Day Duhaime, Lloyd, Legal Definition of Calendar Month Duhaime, Lloyd, Legal Definition of Calendar Week Duhaime, Lloyd, Legal Definition of Calendar Year Follett v WCAB, 551 A. 2d 616; also at 122 Pa. Cmwlth. 58 Always looking up definitions? Save time with our search provider (modern browsers only) If you find an error or omission in Duhaime's Law Dictionary, or if you have suggestion for a legal term, we'd love to hear from you!