Occasionally, a company will find that it must alter its accounting to reflect a change in accounting principle or estimate - or it may locate an accounting error that must be corrected. These changes can have a substantial impact on the reported results of a business from period to period, which can make financial statements much less comparable over time. Accounting Changes and Error Corrections describes the situations in which it is necessary to make adjustments to prior period financial statements, and indicates situations when adjustments are only needed for the current period or in future periods. The differing treatments of changes in accounting principle, accounting estimate, and reporting entity are noted, as is the concept of materiality, which pertains to the correction of accounting errors.