Definition of Calendar Year
A calendar year is the 12 consecutive months from January through December. In other words, it is the 365 days (366 days in a leap year) beginning on January 1 and ending on December 31.
Example of Calendar Years
In the U.S., individuals file their personal income tax returns based on the calendar year of January 1 through December 31. Many U.S. corporations also have accounting and income tax years that coincide with the calendar year of January 1 through December 31. However, U.S. corporations may have an accounting year and income tax year that is not a calendar year.
Examples of Non-calendar Years
If a U.S. corporation has a non-calendar accounting year, it is referred to as a fiscal year.
For example, a U.S. corporation can have a fiscal year that begins on October 1 and ends on the following September 30.
Educational institutions often have fiscal years that begin on July 1 and end on the following June 30. A U.S. retailer can have a fiscal year consisting of 52 weeks that begins on the Sunday closest to February 1 and ends on the Saturday closest to February 1 of the following year.