Advanced Audit and Assurance (International) · Reporting on other assignments

Integrated Reporting and Sustainability Assurance for ACCA AAA

Updated 11 October 2026 · Fact-checked

Sustainability assurance is an engagement where a practitioner gives a conclusion on sustainability or integrated report information against suitable criteria. ISSA 5000 is the IAASB standard for these engagements. You solve questions by defining the subject matter, criteria, level of assurance, risks, evidence and report wording.

Understand Integrated Reporting and Sustainability Assurance

An integrated report explains how an entity creates value over time. It links strategy, governance, performance and prospects across several capitals, such as financial, human, natural and social capital. Sustainability information covers ESG matters such as emissions, safety, workforce data and governance. Much of it is non-financial and often unaudited.

Assurance adds credibility. Investors, lenders and regulators rely on this information. Without assurance, management can overstate achievements. That risk is called greenwashing: presenting the entity as more sustainable than it is, through selective, vague or unsupported claims.

The engagement follows the assurance framework you already know. It has a subject matter (for example, Scope 1 emissions), criteria (for example, a recognised framework or the entity's own stated basis), evidence, and a report. ISSA 5000 is the IAASB's standard for sustainability assurance. It is framework-neutral and can be used by any assurance practitioner, not only accountants. It covers both limited assurance and reasonable assurance. Limited assurance gives a negative-form conclusion, such as nothing has come to our attention. Reasonable assurance gives a positive-form conclusion, with more work and a lower risk of error.

The challenges are practical. Criteria may be immature or self-developed. Data may come from many sites and systems with weak controls. Forward-looking statements, estimates and targets are hard to verify. Practitioners may lack specialist skills, so they may need an expert. Ethics and quality management rules still apply. The practitioner must stay independent and sceptical. The firm must have the competence to take the work on.

In the exam, expect a scenario where a client wants assurance on a sustainability or integrated report. You must advise on acceptance, planning, evidence, risks, and the report. Link every point to the facts given.

Key rules to remember

Elements of an assurance engagement: Three-party relationship + appropriate subject matter + suitable criteria + sufficient appropriate evidence + written report; Use this as a checklist when asked whether an engagement is a valid assurance engagement.
Suitable criteria: Relevance, completeness, reliability, neutrality, understandability; Criteria that fail these tests make the engagement hard to accept or the conclusion hard to give.
Limited assurance conclusion: Negative form: nothing has come to our attention that causes us to believe the information is materially misstated; Less evidence work than reasonable assurance. The report must make the lower level of assurance clear.
Reasonable assurance conclusion: Positive form: in our opinion the information is prepared, in all material respects, in accordance with the criteria; Higher assurance, but still not absolute.
Core evidence approach: Understand the entity and its controls → assess risks of material misstatement → design and perform responses → evaluate evidence → conclude and report; The same risk-based logic as an audit applies, scaled to the assurance level.

How to solve Integrated Reporting and Sustainability Assurance questions

Use this order for any question on assurance over integrated, ESG or sustainability reports. Tie each step to the scenario.

1Identify the subject matter and the intended users. State what is being assured, such as emissions data or the whole integrated report.
2Assess the criteria. Are they suitable and available to users? Say if they are a recognised framework or the entity's own basis.
3Decide the level of assurance, limited or reasonable, and explain what it means for work and wording.
4Consider acceptance. Check competence, need for an expert, independence, access to information and any limits on scope.
5Identify risks, such as greenwashing, weak data systems, estimates, forward-looking claims and consistency with the financial statements.
6Propose procedures: understand controls, test data to source, recalculate, analytical review, inspect documents, enquire, and use experts where needed.
7Evaluate misstatements and the evidence obtained. Consider management representations.
8Conclude on the report: wording, level of assurance, any modification, and the basis of the conclusion.

Quickest way: Subject, criteria, level, risk, evidence, report

When to use it: Use when time is short and the requirement asks for matters to consider or procedures to perform on a sustainability or integrated report.

Write the six headings: subject, criteria, level, risk, evidence, report.
Under each heading, add one or two scenario-specific points.
Always include greenwashing as a risk and name how you would test the specific claim.
Add one professional skills point, such as scepticism about unsupported targets.
Finish with the type of conclusion and any modification.

Common mistakes in Integrated Reporting and Sustainability Assurance

Treating the engagement as a normal financial statement audit.
The risk-based approach looks familiar, so students copy audit wording.
Fix: Use assurance engagement language. Name the criteria, the level of assurance and the form of conclusion.
Ignoring whether the criteria are suitable.
Students jump straight to procedures.
Fix: Test criteria for relevance, completeness, reliability, neutrality and understandability before accepting the work.
Giving a limited assurance conclusion in positive wording.
Students mix up the two levels.
Fix: Limited assurance uses negative form. Reasonable assurance uses positive form.
Listing generic procedures with no link to the scenario.
Students recall a standard list rather than reading the facts.
Fix: Name the actual data, site or claim, such as emissions from overseas plants, and state the specific test.
Forgetting greenwashing and misleading claims.
Students focus on numbers and overlook narrative.
Fix: Check that claims are supported, balanced and consistent with other information, including the financial statements.
Overlooking competence and the use of experts.
Students assume the audit team can do any assurance work.
Fix: State that the team needs sustainability skills, or that an expert must be used and evaluated for competence and objectivity.

Worked examples

Example 1

Zenith plc, an listed manufacturer, asks your firm to provide assurance on the greenhouse gas emissions figures in its sustainability report. The criteria are an internally developed methodology that has not been published. Discuss the matters you would consider before accepting the engagement. (8 marks)

Show the solution

Subject matter: emissions figures are the subject matter. They are measurable, but depend on data from many sites and on estimation factors.
Criteria: the methodology is internal and unpublished. Users cannot see how the figures were prepared, so the criteria fail the test of being available and understandable. They may also lack neutrality and completeness.
Response on criteria: ask management to publish the methodology or adopt a recognised framework. If neither is done, the engagement may not be acceptable, or the report must clearly state the basis used.
Level of assurance: agree with the client whether limited or reasonable assurance is wanted. Limited assurance is more likely given immature criteria and data systems.
Competence and resources: confirm the team has skills in emissions measurement. Consider an expert and assess the expert's competence and objectivity.
Ethics: check independence, including any advice given to Zenith on its emissions systems, which could create self-review or advocacy threats.
Scope and access: confirm access to sites, records and staff. Restrictions on access would be a scope limitation.
Engagement letter: agree the terms, including the subject matter, criteria, level of assurance and form of report.

Answer: Accept only if the criteria are made suitable and available, the team has or can obtain the necessary competence, independence is confirmed, and access is agreed. Otherwise decline or limit the report.

Example 2

Your firm is performing limited assurance on a retailer's sustainability report. The report claims that '100% of our products are sustainably sourced'. Management has only supplier self-declarations. Explain the risk and the procedures you would perform. (6 marks)

Show the solution

Risk: this is a strong, absolute claim supported only by self-declarations. This indicates a risk of greenwashing and material misstatement.
Definition test: ask what 'sustainably sourced' means. If it is not defined or tied to criteria, the claim is vague and cannot be verified.
Procedure: obtain the sourcing policy and any certification standards. Compare the claim to those standards.
Procedure: select a sample of suppliers and inspect certificates or third-party audit reports, checking they are current and from credible bodies.
Procedure: reconcile supplier data to purchase records, to check that all products are covered and none is omitted.
Procedure: enquire of procurement staff and review complaints, media or regulator reports for contrary evidence.
Scepticism: if self-declarations are the only support, the evidence is weak. Seek corroboration from external sources.

Answer: The claim carries a high greenwashing risk. Test the definition, the certificates, the completeness of supplier coverage and any contrary evidence. If management cannot support '100%', ask them to amend the claim. If they refuse, modify the conclusion.

Exam tips

Write about the specific data or claim in the scenario. Generic lists score poorly.
Always state the level of assurance and the matching conclusion wording.
Raise greenwashing, criteria suitability and expert use early. Examiners often reward them.
Use professional skills marks: show scepticism, give a clear recommendation and communicate it in the format asked.
If you are unsure of a detail of ISSA 5000, argue from the assurance framework and ISAE 3000 principles instead of guessing.

Practice questions from Reporting on other assignments

Integrated Reporting and Sustainability Assurance in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

CMA FinalIntegrated Reporting (IR) Framework

Integrated Reporting and Sustainability Assurance: frequently asked questions

What is ISSA 5000?

ISSA 5000 is the IAASB's standard for sustainability assurance engagements. It is framework-neutral and covers limited and reasonable assurance. It can be used by accountants and other assurance practitioners.

What is greenwashing in an assurance context?

Greenwashing is when an entity presents its sustainability performance as better than the evidence supports. The practitioner tests claims for support, balance and consistency with other information. Unsupported claims may lead to a modified conclusion.

What is the difference between limited and reasonable assurance?

Reasonable assurance involves more work and gives a positive-form opinion. Limited assurance involves less work and gives a negative-form conclusion. The report must make the level clear to users.

Can the practitioner use an expert on a sustainability engagement?

Yes. Sustainability matters often need specialist skills, such as emissions measurement. The practitioner must assess the expert's competence and objectivity and evaluate the expert's work.