IAASB 2026 Updates: What Auditors Need to Know

The full December 2026 package

Here’s what takes effect for periods beginning on or after 15 December 2026. For calendar year-end clients, this means your 2027 audits.

ISA 570 (Revised 2024), Going Concern. Approved November 2024, published April 2025. Changes how you identify going concern indicators (gross basis before mitigation), extends management’s required assessment period, and adds two explicit going concern conclusions to every auditor’s report.

ISA 240 (Revised), The Auditor’s Responsibilities Relating to Fraud in an Audit of Financial Statements. Approved March 2025, published July 2025. Removes the “accept records as genuine” default, aligns fraud risk assessment with ISA 315 (Revised 2019), expands communication requirements with TCWG throughout the engagement, and introduces fraud-related KAM requirements.

Narrow-scope amendments to ISQMs, ISAs, and ISRE 2400 (Revised). Approved June 2025, published September 2025. Replaces “listed entity” with “publicly traded entity” throughout the standards to align with the IESBA Code of Ethics. Does not adopt the IESBA “public interest entity” definition at this time.

ISSA 5000, General Requirements for Sustainability Assurance Engagements. Approved and issued November 2024. The first standard in a new 5000-series for sustainability assurance. Covers both reasonable and limited assurance. Replaces ISAE 3410 (Assurance Engagements on Greenhouse Gas Statements), which the IAASB will withdraw when ISSA 5000 becomes effective.

Narrow-scope amendments arising from the IESBA’s external expert provisions. Issued January 2026 after PIOB certification in December 2025. Amends ISAE 3000 (Revised) and ISRS 4400 (Revised) to maintain interoperability with new IESBA Code provisions on using the work of an external expert.

That’s five items on the same effective date. The volume is unusually large, but they cluster into two workstreams for implementation: audit methodology (ISA 240, ISA 570, PTE amendments, external expert amendments) and assurance methodology (ISSA 5000).

ISA 240 (Revised) and ISA 570 (Revised 2024)

These two standards are the core of the December 2026 package. The IAASB designed them as a pair because fraud and financial distress often appear together on the same engagement. A detailed walkthrough of both standards is available in Revised ISA Standards 2026: What’s Changing. The summary here covers only the implementation-critical points.

ISA 570 (Revised 2024) introduces the gross basis requirement: you identify events and conditions that may cast significant doubt on going concern before considering any of management’s mitigating plans. This splits what most firms currently do in one working paper step into two distinct steps. It also extends the required management assessment period to twelve months from the date of approval of the financial statements (ISA 570.21), not the balance sheet date. Every auditor’s report now includes explicit conclusions on going concern regardless of whether a problem was found.

ISA 240 (Revised) removes the previous default that auditors could accept records and documents as genuine. It requires a fraud perspective to be integrated into the ISA 315 risk assessment process rather than treated as a separate exercise. Communication with TCWG about fraud matters must now happen throughout the audit, not only at conclusion. For publicly traded entities, fraud-related matters that required significant auditor attention must be evaluated as potential KAMs.

The interaction between the two standards is the part most likely to trip up implementation. Your ISA 240 fraud risk assessment must reference going concern indicators, and your ISA 570 working paper must reference fraud risk factors. The IAASB made the cross-reference explicit in the application material of both standards. Your going concern checklist and fraud risk matrix need to link to each other in the file.

Narrow-scope amendments: publicly traded entity definition

The narrow-scope amendments approved in June 2025 replace every reference to “listed entity” in the ISQMs and ISAs with “publicly traded entity” (PTE). This aligns IAASB terminology with the IESBA Code of Ethics, which adopted the PTE definition in December 2021 (effective December 2024 for the Code).

The practical impact depends on your client portfolio. If you audit entities whose securities trade on a public market, you already apply the enhanced requirements for listed entities. The definition change doesn’t expand the scope of those requirements. What it does is formalise terminology. The term “listed entity” disappears from the standards entirely.

The IAASB did not adopt the IESBA’s broader “public interest entity” (PIE) definition at this stage. It reaffirmed its commitment to revisit that decision, but the timing depends on global adoption rates of the IESBA PIE revisions. For Dutch firms, the AFM already applies enhanced requirements to PIEs under European regulation, so the local impact is minimal. But if you operate across jurisdictions, you need to track which definition applies where.

Your engagement acceptance and continuance procedures should be updated to use the PTE terminology from December 2026. Any reference to “listed entity” in your ISQM 1 documentation, engagement letters, or quality management policies needs to be replaced.

ISSA 5000: sustainability assurance arrives

ISSA 5000 is not a revision of an existing standard. It’s an entirely new standard in a new series. The IAASB approved it in November 2024 following years of development, and it takes effect on the same December 2026 date as the revised audit standards.

ISSA 5000 applies to all assurance engagements on sustainability information, whether limited or reasonable assurance. It was designed as a standalone standard. Unlike ISAE standards, which require concurrent application of ISAE 3000 (Revised), ISSA 5000 is self-contained. You apply ISSA 5000 alone. ISAE 3000 (Revised) continues to apply to all other non-sustainability assurance engagements.

When ISSA 5000 becomes effective, ISAE 3410 (Assurance Engagements on Greenhouse Gas Statements) will be withdrawn. Any current GHG assurance engagements running under ISAE 3410 will need to transition to ISSA 5000.

For firms that haven’t yet entered the sustainability assurance market, ISSA 5000 matters because the CSRD is driving demand. The EU Corporate Sustainability Reporting Directive requires assurance on sustainability reports starting with large public-interest entities for financial years beginning on or after 1 January 2024. That demand is now reaching mid-tier firms as the directive expands to additional entities. ISSA 5000 gives you the engagement framework. The IESBA simultaneously issued International Ethics Standards for Sustainability Assurance (IESSA), which sets the independence requirements for sustainability assurance work, effective the same date.

The IAASB is monitoring jurisdictional adoption and releasing implementation resources progressively, including an implementation guide published alongside the standard in January 2025.

External expert narrow-scope amendments

In January 2026, the IAASB issued narrow-scope amendments to ISAE 3000 (Revised) and ISRS 4400 (Revised) to maintain interoperability with new provisions in the IESBA Code on using the work of an external expert. These are technical alignment amendments, not substantive changes to audit methodology. They ensure that when the IESBA Code introduces new ethical requirements for situations involving external experts, the IAASB’s assurance and related services standards reference the same concepts.

For most statutory audit firms, the practical impact is limited to ensuring your firm’s quality management policies reference the updated ISAE 3000 (Revised) and ISRS 4400 (Revised) text from the effective date.

What’s coming next: the ISA 500 series and ISA for LCE

The December 2026 effective date is the implementation cliff, but the IAASB’s standard-setting pipeline doesn’t stop there. Two major projects are advancing through 2026.

Audit evidence and risk response (ISA 330, ISA 500, ISA 520)

The IAASB is revising ISA 330 (The Auditor’s Responses to Assessed Risks), ISA 500 (Audit Evidence), and ISA 520 (Analytical Procedures) concurrently. At its March 2026 meeting, the board discussed a first full draft of all proposed revisions. The IAASB has scheduled the exposure draft for these proposed revisions between July and December 2026. Technology is a significant driver of this project: the revisions will address how auditors use automated tools to obtain and evaluate evidence, how to assess the reliability of electronically produced information, and how analytical procedures should work with data analytics.

Separately, the IAASB is scoping a project for targeted standards in the ISA 500 series, including ISA 501 (Specific Considerations for Selected Items), ISA 505 (External Confirmations), and ISA 530 (Audit Sampling). The board discussed a draft project proposal in December 2025 and will review an updated proposal for approval in March 2026.

If your firm uses the ISA 530 audit sampling calculator or the ISA 520 analytical review tool, these revisions will eventually change how those calculations are framed in the standards. No immediate action is needed, but flag the exposure drafts in your firm’s standard-monitoring process for comment.

ISA for less complex entities (LCE)

The IAASB approved a project proposal in December 2025 for the first revision of the ISA for LCE. This revision will update the LCE standard to align with ISA 240 (Revised) and ISA 570 (Revised 2024). A first full draft was scheduled for discussion at the March 2026 board meeting, with an exposure draft expected between July and October 2026.

If you apply the ISA for LCE to smaller statutory audits, the revised version will incorporate the fraud and going concern changes in a proportionate manner. Until it’s finalised, you’ll apply the current ISA for LCE alongside the extant versions of ISA 240 and ISA 570 for LCE-scope engagements.

Worked example: one firm’s implementation timeline

Firm: Dijkstra & Partners Accountants N.V. — Staff: 22 professionals | Clients: 55 statutory audits, 4 ISAE 3402 engagements, 1 GHG assurance engagement | Mix: 48 non-PIE, 7 PIE

Q2 2026: Gap analysis

The methodology partner maps every December 2026 pronouncement against the firm’s current templates. She identifies 14 templates requiring updates: going concern working paper, fraud risk matrix, engagement letter, auditor’s report (four variants), ISQM 1 policy manual, engagement acceptance checklist, and five communication letter templates referencing “listed entity.”

Q3 2026: Template updates

The team splits into two workstreams. Workstream one handles ISA 240, ISA 570, and PTE amendments. Workstream two handles ISSA 5000 (relevant only for the GHG engagement, which transitions from ISAE 3410). The going concern working paper is rebuilt with separate gross identification and mitigation columns. A cross-reference field linking to the fraud risk matrix is added. The auditor’s report templates are updated with the two explicit going concern conclusions per ISA 570 (Revised 2024).

Q4 2026: Training and dry run

All audit staff complete training on both revised standards. The firm runs a mock file review on one completed 2026 engagement, applying the revised standards retroactively to identify gaps. The methodology partner reviews the mock file and compiles a findings list.

January 2027: Go-live

The first 2027 year-end engagement opens with the revised templates. The methodology partner performs an early-stage hot review on the first two files to catch implementation issues before they propagate across the portfolio.

Practical checklist for methodology leads

1. Download the 2025 IAASB Handbook (published January 2026). It includes ISA 570 (Revised 2024), ISA 240 (Revised), the narrow-scope amendments, and ISSA 5000 in their final form. This is your single source document for all template updates.
2. Replace every instance of “listed entity” in your ISQM 1 documentation, engagement letters, and quality management policies with “publicly traded entity.” The narrow-scope amendments affect the ISQMs as well as the ISAs.
3. If your firm has any GHG assurance engagements under ISAE 3410, plan the transition to ISSA 5000 now. ISAE 3410 will be withdrawn when ISSA 5000 becomes effective.
4. Subscribe to the IAASB’s consultation page for the ISA 330/500/520 exposure draft (expected July 2026). Responding to exposure drafts is how mid-tier firms get their implementation concerns heard before a standard is finalised.
5. Build a December 2026 implementation calendar with deadlines for gap analysis, template updates, staff training, and dry-run file reviews. Assign a responsible person for each task. If you wait until Q4 2026, you’re competing with audit season preparation for the same staff time.

Common mistakes to watch for

• Treating the PTE amendments as terminology-only. The definition change also affects which engagements trigger the enhanced requirements in ISA 240 (Revised) and ISA 570 (Revised 2024). If you’re unsure whether a client meets the PTE definition in your jurisdiction, the engagement acceptance checklist needs a specific prompt for that assessment.
• Ignoring the ISSA 5000 transition for GHG engagements. ISAE 3410 will be withdrawn. Any firm with a live GHG assurance engagement that hasn’t mapped its methodology to ISSA 5000 by December 2026 will be operating without a valid standard.
• Implementing ISA 240 and ISA 570 separately without building the cross-references between them. The IAASB explicitly designed these standards to interact. Inspectors will look for evidence that the fraud risk assessment and going concern assessment reference each other.

Related content

Frequently asked questions

Further reading and source references

• ISA 570 (Revised 2024), Going Concern: approved November 2024, published April 2025.
• ISA 240 (Revised), The Auditor’s Responsibilities Relating to Fraud: approved March 2025, published July 2025.
• ISSA 5000, General Requirements for Sustainability Assurance Engagements: approved and issued November 2024.
• Narrow-scope amendments (PTE): approved June 2025, published September 2025.
• External expert narrow-scope amendments: issued January 2026 after PIOB certification December 2025.
• 2025 IAASB Handbook: published January 2026, contains all final standards and amendments effective December 2026.
• IAASB March 2026 board meeting materials: include first full drafts of proposed ISA 330, ISA 500, and ISA 520 revisions.