Prior Period Adjustment

A prior period adjustment is an accounting correction made when a company discovers a material error in financial statements it has already issued. Rather than recording the correction in the current year's income statement, the company restates the comparative figures for the earlier periods shown and adjusts the opening balance of retained earnings for the earliest period presented. This keeps the current year's results free of amounts that belong to earlier years and makes the periods comparable.

In US GAAP, the rules are in ASC 250, Accounting Changes and Error Corrections; under IFRS they are in IAS 8. Errors include mathematical mistakes, misapplication of accounting principles, oversights and misuse of facts that existed when the statements were prepared, and fraud. A prior period adjustment is different from a change in accounting estimate, such as revising a useful life based on new information, which is applied prospectively and does not restate earlier years.

• Determine the effect of the error on each prior period presented and on periods before them.
• Restate the comparative financial statements as if the error had never happened.
• Adjust the opening balance of retained earnings (and other affected balances) for the cumulative effect on periods before those presented, net of tax.
• Disclose the nature of the error, the effect on each line item and on earnings per share, and the cumulative effect on retained earnings.

Under IFRS, if it is impracticable to determine the effect on a particular period, the company restates from the earliest date it can.

In preparing its 2026 statements, a company discovers that it forgot to record $200,000 of depreciation on equipment in 2025. Its tax rate is 25 percent, and the error also affects the tax figures. The after-tax effect is:

Here $\text{Pre-tax error}$ is the amount by which pre-tax profit was misstated and $t$ is the tax rate. Net income for 2025 was overstated by $200,000 times 0.75, or $150,000. The company restates its 2025 comparative figures, increasing depreciation expense by $200,000, reducing income tax expense by $50,000 and reducing 2025 net income by $150,000. On the balance sheet, accumulated depreciation rises by $200,000, a tax receivable or deferred tax balance changes by $50,000, and retained earnings fall by $150,000. In the 2026 statement of retained earnings, opening retained earnings are shown as originally reported, less the $150,000 prior period adjustment. The correcting entry in 2026 debits retained earnings $150,000 and the tax account $50,000, and credits accumulated depreciation $200,000; it does not pass through 2026 income.

For US public companies, the Securities and Exchange Commission and practitioners distinguish two kinds of correction. When an error is material to prior statements, those statements can no longer be relied upon: the company must file an Item 4.02 Form 8-K announcing non-reliance and reissue the earlier statements, a so-called "Big R" restatement. When an error is immaterial to prior periods but correcting it in the current period would be material, the company revises the comparative figures in its next filing without reissuing earlier reports, a "little r" revision. SEC Staff Accounting Bulletin No. 108 explains how errors should be evaluated using both balance sheet and income statement approaches.

Restatements can damage a company's credibility, trigger lawsuits and loan covenant breaches, and lead to management changes, so investors watch them closely. A pattern of corrections may point to weak internal control over financial reporting. Prior period adjustments differ from voluntary changes in accounting principle, which are also applied retrospectively but are not errors. For small, immaterial errors, companies simply record a correcting entry in the current period. The effect of any restatement is visible in comparative financial statements, and the related audit implications are reflected in the auditor's report. The standards on error correction are maintained by the FASB and the IASB.