IFRS 18 Uncovered: Preparing Your OneStream Environment

A new reporting era is coming. With IFRS 18 set to reshape how organizations classify, present, and communicate financial performance, finance teams must begin preparing their data models, reporting structures, and systems well ahead of the 2027 effective date.

This article provides an overview of the standard and outlines how organizations can proactively prepare to comply with IFRS 18 through a structured approach.

Understanding IFRS 18

IFRS 18 establishes new overarching requirements for the presentation and disclosure of financial statements, replacing International Accounting Standards (IAS). 1. The latest standard introduces a revised structure for the statement of profit or loss by requiring entities to present two new mandatory subtotals: operating profit and profit before financing and income taxes.

In addition, IFRS 18 requires income and expenses to be classified into five categories: operating, investing, financing, income tax, and discontinued operations, three of which are new.

The classification of income and expenses will depend significantly on an entity’s core business activities and, as a result, may vary across industries. For most organizations, the majority of income and expenses are expected to fall within the operating category, making careful assessment and consistent application essential.

5 Classifications of Income and Expenses

Income and expenses related to OPERATIONS

Returns and expenses
pertaining to INVESTING

Income and expenses related to obtaining FINANCING

INCOME TAXES

Income and expenses from DISCONTINUED OPERATIONS

IFRS 18 also introduces enhanced requirements for Management-defined Performance Measures (MPMs). MPMs are subtotals of income and expenses used in public communications that reflect the management’s view of financial performance. These measures must be disclosed transparently, clearly explained, and reconciled to the most directly comparable IFRS-defined subtotal, increasing both accountability and comparability.

The standard further strengthens principles regarding aggregation and disaggregation. Entities must apply tighter rules when grouping and labelling line items, with increased disaggregation required for material items. Amounts labeled as “Other” will need to be carefully reviewed and, if significant, either disaggregated or clearly explained to provide users with meaningful financial information.

Finally, entities should assess the broader impact of IFRS 18 across the financial statements, including the statement of cash flows, particularly with respect to the classification of interest and dividends. These changes may require updates to existing policies, systems, and reporting processes to ensure consistent and compliant application.

Effective Date and Applicability

IFRS 18 becomes effective for annual reporting periods starting from 1 January 2027. Early adoption is allowed if it is disclosed.

Transition Requirements

Application is retrospective, requiring restatement of comparative periods.
Entities are not required to provide full IAS 8 quantitative impact disclosures for currentperiod transitions.
Comparatives for both annual and interim statements must be reconciled to previously reported figures.

This timeline means organizations need to begin data modeling, process, and system adjustments well before 2027.

Who Must Comply

IFRS 18 applies to all entities that prepare financial statements in accordance with IFRS Accounting Standards and present a statement of profit or loss. This includes:

Publicly listed companies reporting under IFRS
Private companies applying IFRS either voluntarily or due to contractual obligations
Multinational groups using IFRS for consolidated financial reporting
Subsidiaries with IFRS-based group reporting
The standard applies equally to financial institutions and non-financial corporates, regardless of industry

Preparing OneStream for IFRS 18

For organizations building a case for CPM transformation—or those already implementing CPM—IFRS 18 presents a natural opportunity to update the Chart of Accounts and mapping structures to align with the new categories.

Implementing these changes early in the design phase helps avoid costly rework and ensures more efficient and audit-ready reporting cycles. AMCO’s recommended approach for existing OneStream customers includes the following phases:

1. Assessment

New P&L Structure, assessment, and gap analysis

Understanding and reviewing the current OneStream setup, such as the Chart of Accounts, P&L hierarchies, including subtotals, financial statements, notes and disclosures that have already been built.
Map the new P&L hierarchy and subtotals, as well as disclosures in accordance with IFRS 18.
Identify missing mandatory subtotals and non-compliant aggregation, and list non-IFRS KPIs vs. MPM definition.

2. Validate

Design and define how IFRS 18 will be implemented in OneStream.

Decide on how to convert the chart of accounts to adhere to the new P&L structure, whether through extensions, using attributes, etc.
Check if data sets will be changed and if new transformation rules will be affected.
Review accounts that need disaggregation, including new and mandatory subtotals.
Specify the process for setting up MPMs when creating a new scenario, adding new account totals, or configuring validation and confirmation rules.
Define all the reports and forms that need to be added and changed.

3. Develop

Implement and test IFRS 18 in the application.

Update the metadata
Update mapping
Build rules
Create new reports
Update workflow
Testing and more as defined in the implementation plan

4. Deploy

Roll out the redesigned structure across the application and ensure all updates are thoroughly validated and ready for operational use.

Conduct User Acceptance Testing (UAT)
Parallel runs
Deploy the solution and its relevant components
Deliver training to end users
Prepare for transition to go live
Go-live support

5. Evolve

After go-live, complete post-deployment support activities, finalize project closure, and transition the application to applicable managed service programs.

Your Next Steps Toward IFRS 18 Readiness

IFRS 18 marks a fundamental shift in performance reporting, bringing greater clarity, consistency, and transparency to financial statement presentation. For organizations using OneStream, the question is not whether the platform can support IFRS 18—it can—but how efficiently and effectively it is designed to do so.

By preparing early, organizations can use OneStream’s unified data model and extensible design to incorporate IFRS 18 requirements without disrupting consolidation or close processes. A structured approach ensures clean integration of new classifications, subtotals, and MPM disclosures while maintaining flexible internal reporting.

Ultimately, organizations that approach IFRS 18 as a transformation opportunity rather than a compliance exercise will be best positioned to enhance financial communication, improve stakeholder confidence, and future-proof their OneStream platform for evolving reporting standards.

By: Veradel Leprozo, Consulting Director

Looking for Expert Guidance on Implementing IFRS 18?

IFRS 18 introduces new requirements that demand clear structures, accurate classifications, and well‑designed reporting processes. AMCO’s specialists can help you evaluate your current OneStream setup, refine your financial models, and implement the changes needed for consistent and compliant reporting.

Connect with our team to build a solid, future‑ready approach to IFRS 18.