Calendar year definition

What is a Calendar Year?

A calendar year is a twelve-month period that begins on January 1 and ends on December 31. It is based on the Gregorian calendar, and is used in most countries to plan social and business events. The calendar year is the basis for numerous tax filings. It tends to be the default fiscal year for entities that have not specifically established a different date range for their fiscal years.

The calendar year contains either 365 or 366 days, depending upon whether it is a leap year.