QuickBooks Dictionary
Accounting period
An accounting period is the 12-month period on the basis of which the taxpayer's records are kept. If no books are kept or if no other period is specified, the accounting period is the calendar year. If the books are kept on the basis of a 12-month period ending with a month other than December, the accounting period is a fiscal year. A special 52-53-week accounting period is also recognized for income tax purposes.