Apply IAS 8 to policies, estimates and prior-period errors
Use IAS 8 to classify a reporting change and select retrospective or prospective treatment at the syllabus level.
Cambridge International AS & A Level Accounting 9706, 2026–2028 syllabus, Version 2. These lessons cover the nine named IAS at the main-provisions level described in Cambridge teacher guidance, the stated ethical principles, audit and stewardship. Practice is self-checked, not an official Cambridge grade. Full timed Papers 1–4 and human subject-teacher review remain outstanding.
Before you begin
- Use the Topic 1.5 and 3.1 statement skills: identify the reporting period, distinguish profit from cash, and explain how a reporting choice affects users of financial statements.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
An invoice received before authorisation was accidentally omitted from last year's statements. What is the likely classification?
What you will learn
- Distinguish an accounting policy from an estimate and an error
- Apply a policy change retrospectively where required
- Apply estimate changes prospectively and correct material prior-period errors
Identify what has changed before choosing a treatment
An accounting policy is a principle, basis or method used to prepare statements. A change in policy is made when a standard requires it or when it produces more relevant and reliable information, and similar transactions are treated consistently. At the syllabus level, a policy change is generally applied retrospectively, with comparative information restated where practicable.
An estimate changes when new information or changed circumstances revise an uncertain amount, such as an asset's remaining useful life. It is not an error merely because the estimate differs from the outcome. The effect is recognised prospectively in the current and, where relevant, future periods.
Correct material prior-period errors
A prior-period error arises when reliable information available at the time was omitted or misused. Examples include a calculation mistake or failing to apply the required policy. A material error is corrected retrospectively in the first statements authorised after discovery, with comparatives restated where practicable and the nature and amount disclosed.
Use the cause, not simply the size of the resulting difference, to classify the event. New evidence that changes a reasonable estimate is different from discovering that an available invoice was left out. The treatment communicates whether the past was misstated or today's estimate has changed.
Pause and explain
When may an accounting policy change be made?
Worked example
A machine was expected to last ten years. After an engineering inspection in year four, the remaining useful life is revised to three years. Classify the change and state the broad treatment.
Show the worked solution
- The original estimate was based on information available at that time.
- The inspection provides new information about remaining life, so this is a change in estimate rather than a prior-period error.
- Apply the revised depreciation prospectively over the remaining useful life, using the updated carrying amount and residual value if relevant.
Answer This is a change in estimate. Revise depreciation prospectively; do not restate earlier periods solely because a reasonable estimate changed.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Classify each event: (1) a required standard changes the inventory policy; (2) new customer data changes the expected irrecoverable amount; (3) an old supplier invoice was omitted despite being available.
Give me a hint
Ask whether the rule changed, new uncertainty information arrived, or available past information was misused.
Compare my reasoning
- (1) Policy change, because a new standard requires a different accounting basis.
- (2) Estimate change, because new information changes an uncertain amount.
- (3) Prior-period error, because available reliable information was omitted.
(1) Policy change; (2) estimate change; (3) prior-period error. The broad treatments are retrospective for a policy change or material error, and prospective for an estimate.
Look for these in your work
- Three categories distinguished
- Cause used to classify
- Treatment distinction stated
A company discovers that a material depreciation calculation error overstated prior profit by $8,000. State the broad correction and two items to communicate.
Give me a hint
Separate correcting the past misstatement from recording a new estimate.
Compare my reasoning
- Correct the material prior-period error retrospectively in the first statements authorised after discovery, subject to practicability.
- Restate comparative figures where practicable.
- Disclose the nature of the error and the amount of correction.
Apply a retrospective correction where practicable, restate comparatives and disclose the nature and $8,000 effect of the error.
Look for these in your work
- Retrospective approach stated
- Comparatives considered
- Nature and amount disclosed
A finance manager wants to change the depreciation method because the new method better reflects how the asset is consumed. What should be examined before deciding whether this is a policy or estimate change?
Give me a hint
Focus on whether the underlying measurement basis changed or new information revised a useful-life or usage estimate.
Compare my reasoning
- Identify whether the accounting method itself is changing or whether assumptions such as useful life, residual value or usage pattern have changed.
- Review whether the new information makes the financial statements more relevant and reliable and whether the standard permits the treatment.
- Explain and apply the change consistently; do not label a change merely to avoid restating information or to target profit.
Examine the reason and substance. A revised consumption pattern based on new information may be an estimate change; a change in the underlying accounting basis may be a policy change. Apply the relevant standard and explain the effect transparently.
Look for these in your work
- Substance of change assessed
- New information separated from method
- Transparent application required
Common mistakes
- Calling every revised amount an error
- Restating prior periods for a new estimate
- Treating a deliberate policy switch as an estimate change
What can you explain now?
A new reliable estimate of an asset's remaining life is usually applied how?
Compare with the explanation
Prospectively
A change in estimate affects the current and relevant future periods, not earlier periods.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Complete the three-way distinction: policy change, estimate change and prior-period error each arises because…
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.