### Question
How does the law define annual accounting period?


### Answer
Under *26 CFR § 1.441-1T*, **annual accounting period** is defined as:

> the annual period (calendar year or fiscal year) on the basis of which the taxpayer regularly computes his income in keeping his books

#### Citation:
  - *26 CFR § 1.441-1T*
  - Heading: **Title 26—Internal Revenue > PART 1—INCOME TAXES (Continued) > CHAPTER I—INTERNAL REVENUE SERVICE,**

