According to ASBJ Statement 24, accounting changes are defined those including:
- Changes in accounting policies,
- Changes in presentation methods, and
- Changes in accounting estimates.
Error corrections are defined separately form accounting changes.
An entity changes should not change its accounting policies unless justifiable reasons for doing so. If an entity changes its accounting policies in accordance with new accounting standards, its should comply with the provisions in that standard. If an entity changes its accounting policies with other justifiable reasons, it should apply the new accounting policies retrospectively so as to restate the prior-year financial statements as if they were already applied in previous years..
If an entity changes its presentation method so that its financial statements are more faithfully representative, it should restate its prior-year financial statements retrospectively.
If an entity changes its accounting estimates, it should account for:
- Such change during the period when the change affects the financial statements in that period; and
- Such change over the periods prospectively when the change affects the financial statements in following more than one periods.
If an error in the amounts previously reported is found in the period, it should be reflected retrospectively in the prior-year financial statements.
The ASBJ provides a summary in English here.