Time Period Assumption

This accounting principle assumes that it is possible to report the complex and ongoing activities of a business in relatively short, distinct time intervals such as the five months ended May 31, 2017, or the 5 weeks ended May 1, 2017. The shorter the time interval, the more likely the need for the accountant to estimate amounts relevant to that period. For example, the property tax bill is received on December 15 of each year. On the income statement for the year ended December 31, 2016, the amount is known; but for the income statement for the three months ended March 31, 2017, the amount was not known and an estimate had to be used.

It is imperative that the time interval (or period of time) be shown in the heading of each income statement, statement of stockholders' equity, and statement of cash flows. Labeling one of these financial statements with "December 31" is not good enough–the reader needs to know if the statement covers the one week ended December 31, 2017 the month ended December 31, 2017 the three months ended December 31, 2017 or the year ended December 31, 2017.