### Question
What is the definition of calendar year?


### Answer
The definition of **calendar year** is as follows in *26 CFR § 1.441-1T*:

> a period of 12 months ending on December 31. A taxpayer who has not established a fiscal year must make his return on the basis of a calendar year

#### Citation:
  - *26 CFR § 1.441-1T*
  - Heading: **PART 1—INCOME TAXES (Continued) > SUBCHAPTER A—INCOME TAX (Continued) > SUBCHAPTER A—INCOME TAX (Continued)**

