The time period principle is the concept that a business should report the financial results of its activities over a standard time period, which is usually monthly, quarterly, or annually. Once the duration of each reporting period is established, use the guidelines of Generally Accepted Accounting Principles or International Financial Reporting Standards to record transactions within each period.
You must include in the header of a financial statement the time period covered by the statement. For example, an income statement or statement of cash flows may cover the "Eight Months ended August 31." However, the balance sheet is dated as of a specific date, rather than for a range of dates. Thus, a balance sheet header might state "as of August 31."
The time period principle is also known as the time period concept or time period assumption.