- US GAAP
ASC 270-10 notes the following:
The Interim Reporting Topic clarifies the application of accounting principles and reporting practices to interim financial information, including interim financial statements and summarized interim financial data of publicly traded companies issued for external reporting purposes. Interim financial information may include current data during a fiscal year on financial position, results of operations, comprehensive income, and cash flows. This information may be issued on a monthly or quarterly basis or at other intervals and may take the form of either complete financial statements or summarized financial data. Interim financial information often is provided for each interim period or on a cumulative year-to-date basis, or both, and for the corresponding periods of the preceding year.
The determination of the results of operations on a meaningful basis for intervals of less than a full year presents inherent difficulties. The revenues of some entities fluctuate widely among interim periods because of seasonal factors, while in other entities heavy fixed costs incurred in one interim period may benefit other periods. In these situations, financial information for periods of less than a full year may be of limited usefulness. In other situations costs and expenses related to a full year's activities are incurred at infrequent intervals during the year and need to be allocated to products in process or to other interim periods to avoid distortion of interim financial results. In view of the limited time available to develop complete information, many costs and expenses are estimated in interim periods. For example, it may not be practical to perform extensive reviews of individual inventory items, costs on individual long-term contracts and precise income tax calculations for each interim period. Subsequent refinement or correction of these estimates may distort the results of operations of later interim periods. Similarly, the effects of disposal of a segment of an entity and extraordinary, unusual, or infrequently occurring events and transactions on the results of operations in an interim period will often be more pronounced than they will be on the results for the annual period. Special attention must be given to disclosure of the impact of these items on financial information for interim periods.