Key Points
- A change in accounting policy requires retrospective application as if the new policy had always been in place, unless a specific IFRS provides transitional relief.
- A change in accounting estimate is applied prospectively from the period of the change, with no restatement of prior periods.
- Prior-period errors must be corrected by restating the earliest comparative period presented, which often triggers restatement of opening retained earnings.
- Distinguishing a policy change from an estimate change determines whether comparatives are restated or left untouched.
What is Accounting Policies, Changes in Estimates and Errors?
IAS 8.5 defines accounting policies as the specific principles, bases, conventions, rules, and practices an entity applies in preparing its financial statements. When an entity changes a policy voluntarily (for instance, moving from the cost model to the revaluation model for a class of assets), IAS 8.19 requires retrospective application. The entity restates comparatives as though the new policy had been in force from the start, adjusting opening retained earnings for the cumulative effect of periods before those presented.
Changes in accounting estimates work differently. IAS 8.32 requires prospective treatment only. Revising useful life or updating a provision measurement reflects new information, not a correction. The revised estimate flows through profit or loss in the current and future periods without touching comparatives. IAS 8.35 adds that if distinguishing a policy change from an estimate change is difficult, the entity treats the change as a change in estimate.
Prior-period errors (omissions or misstatements in earlier financial statements) require retrospective restatement under IAS 8.42. The entity corrects the error in the earliest period presented and adjusts opening balances accordingly. ISA 240.11 reminds the auditor that a prior-period error, once identified, must be evaluated to determine whether it resulted from fraud or from an unintentional misstatement, because the response differs.
Worked example
Client: Swedish forestry and paper company, FY2025, revenue EUR 75M, IFRS reporter. During the FY2025 audit, the engagement team identifies two matters: Bergstrom changed its method for measuring biological assets (standing timber) from a cost-based approach to a fair-value model as required by IAS 41, and the team discovered that FY2024 inventory had been overstated by EUR 620,000 due to an input error in the weighted-average cost calculation.
Step 1 — Classify the biological asset measurement change
Bergstrom's move to fair value for biological assets is mandatory under IAS 41.12. Although this looks like a policy change, IAS 41 itself provides specific transitional guidance. IAS 8.19(b) requires the entity to follow the transition provisions of the new standard when they exist. The engagement team confirms that IAS 41 mandates fair-value measurement, so no choice is involved.
Documentation note: record the classification as a mandatory policy change under IAS 8.19(b), referencing IAS 41.12. Document that the entity applied the transition provisions of IAS 41 rather than the general retrospective approach of IAS 8.22.
Step 2 — Apply the policy change retrospectively
Bergstrom restates the FY2024 comparative balance sheet. Standing timber previously carried at EUR 8.4M under the cost approach is remeasured at fair value of EUR 10.1M. The EUR 1.7M difference (net of deferred tax of EUR 408,000 at the Swedish corporate rate of 20.6%) increases opening retained earnings for FY2024 by EUR 1,292,000. The FY2024 income statement is also restated to reflect fair-value gains previously unrecognised.
Documentation note: record the comparative restatement under IAS 8.22, the deferred tax adjustment under IAS 12, and the disclosure of the nature and amount of the change required by IAS 8.28(a)–(f). Cross-reference the timber valuation report from the external forestry appraiser.
Step 3 — Correct the prior-period inventory error
The EUR 620,000 inventory overstatement in FY2024 is a prior-period error under IAS 8.41. Bergstrom restates the FY2024 comparative figures: inventory decreases by EUR 620,000, cost of sales increases by the same amount, and profit before tax falls by EUR 620,000. After deferred tax (EUR 127,720 at 20.6%), retained earnings at 1 January 2025 decrease by EUR 492,280.
Documentation note: record the error correction under IAS 8.42, including the nature of the error (input error in weighted-average cost), the line items affected, and the amount of the correction for each prior period presented. Document the evaluation under ISA 240.11 confirming the error was unintentional.
Step 4 — Assess whether any estimate changes require separate treatment
Bergstrom also revised the estimated useful life of its paper mill equipment from 15 years to 12 years based on updated engineering assessments. IAS 8.36 requires prospective application. The revised depreciation charge applies from 1 January 2025 onward. No restatement of FY2024 comparatives is needed.
Documentation note: record the estimate change under IAS 8.36, the basis for the revised useful life (engineering report dated November 2025), and the effect on the current-period depreciation charge. Disclose the nature and amount per IAS 8.39.
Conclusion: the worked example produces three distinct treatments on one engagement (retrospective policy change, retrospective error correction, prospective estimate change), and each is defensible because the classification drives the accounting and the documentation ties each treatment to its IAS 8 paragraph.
Why it matters in practice
- Teams frequently misclassify a change in estimate as a change in accounting policy, triggering unnecessary retrospective restatement. IAS 8.35 provides a tiebreaker: when the distinction is unclear, the entity treats the matter as a change in estimate. Auditors who do not apply this tiebreaker risk accepting comparative restatements that the standard does not require, which creates additional audit work and introduces restatement risk into the prior-period opinion.
- Prior-period error corrections often lack the disclosures mandated by IAS 8.49. The entity must disclose the nature of the error, the amount of the correction for each prior period, and the amount of the correction at the beginning of the earliest prior period presented. The FRC's 2022 thematic review of restatements noted that several entities corrected errors without providing the required line-item detail, leaving users unable to assess the effect on individual financial statement lines.
Change in accounting policy vs. change in accounting estimate
| Dimension | Change in accounting policy | Change in accounting estimate |
|---|---|---|
| Definition | Alters the recognition, measurement, or presentation basis applied to transactions (IAS 8.5) | Revises a measurement input based on new information or developments (IAS 8.32) |
| Application method | Retrospective: restate comparatives as if the new policy had always applied (IAS 8.22) | Prospective: apply from the period of the change onward only (IAS 8.36) |
| Effect on prior periods | Opening retained earnings and comparative figures are adjusted | No adjustment to prior periods |
| Disclosure trigger | IAS 8.28 requires disclosure of the nature, reasons, and amounts for each line item | IAS 8.39 requires disclosure of the nature and amount of the change, or a statement that the amount is impracticable to estimate |
| Audit focus | Verify that retrospective restatement is complete and that transition provisions were followed correctly | Verify that the revised estimate is supported by current evidence and that no retrospective adjustment was made |
The distinction controls whether the auditor re-examines prior-period figures. When an entity misclassifies an estimate change as a policy change, the resulting restatement introduces unnecessary restatement risk and may trigger additional procedures on comparative information under ISA 710.
Related terms
Frequently asked questions
How do I distinguish a change in accounting policy from a change in estimate?
A policy change alters the recognition, measurement, or presentation basis (for example, switching depreciation models from cost to revaluation). An estimate change revises a measurement input within the same policy framework (for example, updating useful life). IAS 8.35 states that when the distinction is difficult, the entity treats the change as a change in estimate and applies it prospectively.
What disclosures does IAS 8 require for a prior-period error correction?
IAS 8.49 requires the entity to disclose the nature of the error, the amount of the correction for each financial statement line item affected, the correction to basic and diluted earnings per share, and the amount of the adjustment at the beginning of the earliest prior period presented. If retrospective restatement is impracticable for a particular prior period, the entity discloses that fact and explains why under IAS 8.50.
Does a first-time adoption of an IFRS count as a voluntary policy change?
No. When an entity applies a new or revised IFRS for the first time, IAS 8.19(b) requires the entity to follow the transition provisions of that standard. Only when no specific transition provisions exist does the general retrospective approach of IAS 8.22 apply. First-time adoption of IFRS as a whole framework falls under IFRS 1, not IAS 8.