IFRS 18 vs IAS 1: Key Differences and What Changes in 2027
IFRS 18 replaces IAS 1 Presentation of Financial Statements for annual periods beginning on or after 1 January 2027. The two standards share the same broad purpose, but IFRS 18 rewrites the rules on income statement structure in ways that will force most reporting teams to reopen their chart of accounts, reclassify P&L lines, and redesign disclosures before the first 2027 filing.
This comparison cuts through the overlap to show exactly where the standards diverge, which changes are genuinely new versus cosmetic, and what the verdict means for your 2027 implementation.
Key takeaway: IFRS 18 does not change recognition or measurement. It changes how you present and disclose financial performance, and the structural changes to the income statement are the most significant update to IFRS financial reporting in a generation.
IFRS 18 vs IAS 1: What Stays the Same
Most of IAS 1 survives into IFRS 18. The IASB confirmed that it did not reconsider all aspects of IAS 1 when developing IFRS 18, focusing instead on the statement of profit or loss. The following core principles carry over with limited or no change:
- The requirement to present a complete set of financial statements (statement of financial position, statement of profit or loss, statement of changes in equity, statement of cash flows, and notes)
- Going concern assessment requirements
- The distinction between current and non-current assets and liabilities
- Materiality principles governing what must be disclosed
- The requirement to present at least one comparative period
- General fair presentation and compliance requirements
Some IAS 1 content migrates into other IFRS standards rather than disappearing. Accounting policy disclosures, for instance, move to IFRS 7 and other standards. The net effect is that IFRS 18 is a targeted intervention on income statement presentation, not a wholesale rewrite of financial statement architecture.
The Five-Category Income Statement: Where IFRS 18 Breaks from IAS 1
This is the structural break. Under IAS 1, companies classify income and expenses with significant flexibility. There is no required definition of operating profit, no mandated subtotals between revenue and profit before tax, and no standard framework for separating financing from operating activity in the P&L. That flexibility produced comparability problems: two companies in the same industry could present materially different income statement structures, making line-by-line comparison unreliable.
IFRS 18 fixes this by requiring all income and expenses to be classified into one of five categories:
- Operating, the residual category; everything not classified elsewhere
- Investing, income and expenses from investments in associates, joint ventures, unconsolidated subsidiaries, cash and cash equivalents, and other assets that generate returns independently of the entity's other resources
- Financing, income and expenses from liabilities that arise solely from raising finance (bank loans, loan notes) plus interest on other liabilities such as lease liabilities and pension obligations
- Income taxes, tax income and expenses under IAS 12
- Discontinued operations, per IFRS 5
Under IAS 1, the investing and financing distinction existed in the cash flow statement but not in the P&L. IFRS 18 imports that logic onto the face of the income statement.
The "Specified Main Business Activity" Exception
One of the more judgment-intensive elements of IFRS 18 has no IAS 1 equivalent. If an entity's main business activity is investing in assets (real estate funds, investment companies) or providing finance to customers (banks, captive finance arms), it reclassifies certain items that would otherwise sit in investing or financing into the operating category instead. Interest income on customer loans at a bank, for example, moves to operating. Equity-method income from associates, however, always stays in investing regardless of main business activity.
Mandatory Subtotals: IAS 1 vs IFRS 18 Side by Side
| Element | IAS 1 | IFRS 18 |
|---|---|---|
| Operating profit subtotal | Optional; no standard definition | Required; defined term |
| Profit before financing and income taxes | Not required | Required |
| Profit or loss | Required | Required |
| Income statement categories | No prescribed categories | Five prescribed categories |
| Definition of "operating" | Not defined | Residual (everything not in another category) |
| Investing/financing split in P&L | Not required | Required |
IFRS 18 mandates two new subtotals that IAS 1 never required:
- Operating profit or loss, the sum of all items in the operating and investing categories
- Profit or loss before financing and income taxes, operating profit plus the financing category
For a detailed walkthrough of how these subtotals are calculated and what reclassifications they trigger, see Finrep's IFRS 18 mandatory subtotals guide.
The practical sting: companies that already present an "operating profit" line under IAS 1 may find their existing number does not match the IFRS 18 definition. Interest income on cash balances, for instance, often sits above the operating profit line today but must move to the investing category under IFRS 18, pulling it below operating profit.
Management-Defined Performance Measures: A Genuinely New Disclosure Layer
IAS 1 says nothing about non-IFRS performance metrics. IFRS 18 introduces a formal disclosure regime for management-defined performance measures (MPMs), subtotals of income and expenses that management uses publicly to communicate financial performance and that are not required or defined by IFRS.
Adjusted EBITDA, adjusted operating profit, and underlying earnings are the obvious candidates. Under IFRS 18, if you use any such measure in public communications (earnings releases, investor presentations, annual reports), you must:
- Define the MPM and explain why management uses it
- Reconcile it to the most directly comparable IFRS 18 subtotal
- Disclose the tax effect and the effect on non-controlling interests
- Present the reconciliation in the notes, not just in non-GAAP supplementary schedules
This is a structural change in how companies communicate with investors, not just a formatting adjustment. For the full MPM framework, see Finrep's IFRS 18 management-defined performance measures walkthrough.
Aggregation and Disaggregation: Tighter Rules Under IFRS 18
IAS 1 requires disaggregation of material items but leaves significant discretion on how to group line items. IFRS 18 tightens this with explicit principles: items must be aggregated or disaggregated based on shared characteristics, and the result must provide a useful structured summary without obscuring material information.
The most operationally significant change here applies to companies that present operating expenses by function (cost of sales, selling expenses, administrative expenses). Under IFRS 18, those companies must also disclose a breakdown of expenses by nature (employee costs, depreciation, raw materials) in the notes. IAS 1 encouraged this but did not require it. IFRS 18 mandates it.
For companies currently presenting by function only, this means building a parallel expense analysis by nature, which may require chart-of-accounts changes and new data capture processes.
Retrospective Application: The 2026 Restatement Requirement
IFRS 18 applies retrospectively. If your first IFRS 18 annual report covers the year ending 31 December 2027, you must restate the 2026 comparative period under IFRS 18 rules. That means the 2026 income statement, presented as a comparative in your 2027 financial statements, must show the new categories, the new subtotals, and the MPM disclosures as if IFRS 18 had always applied.
This is not a transition relief. It is a hard requirement, and it means the practical preparation window is now, not in late 2026. Your 2026 data needs to be captured in a way that supports IFRS 18 reclassification from the start of the comparative period.
For a phased implementation roadmap, see Finrep's IFRS 18 implementation guide.
IFRS 18 vs IAS 1: The Verdict
IAS 1 gave preparers flexibility. IFRS 18 trades that flexibility for comparability. The table below summarises where the standards genuinely diverge:
| Area | IAS 1 verdict | IFRS 18 verdict |
|---|---|---|
| Income statement structure | Flexible; no prescribed categories | Structured; five mandatory categories |
| Operating profit definition | Undefined; company-specific | Defined; consistent across all reporters |
| Mandatory subtotals | Profit before tax only | Operating profit + profit before financing and tax |
| MPM disclosure | No requirement | Formal reconciliation in notes required |
| Expense disaggregation (by function presenters) | Encouraged by nature disclosure | Mandatory by nature disclosure in notes |
| Recognition and measurement | Unchanged | Unchanged |
| Effective date | In force since 1997 | 1 January 2027 (early adoption permitted) |
The IASB's intent was not to rebuild the financial statements from scratch. It was to solve a specific problem: investors could not reliably compare operating performance across companies because "operating profit" meant something different to every preparer. IFRS 18 solves that problem at the cost of significant implementation work for most reporters.
Companies with diverse operations, multiple business segments, or a history of prominent adjusted metrics will feel the most friction. Banks and insurers with specified main business activities face additional classification judgment. For those entities, the operating/investing/financing boundary is not a formatting question; it is a substantive accounting decision that will require documented policies and auditor alignment before 2027.
FAQ
Does IFRS 18 change how assets and liabilities are recognised or measured? No. IFRS 18 is purely a presentation and disclosure standard. Recognition and measurement rules under other IFRS standards (IFRS 9, IFRS 16, IAS 36, and so on) are unchanged.
When does IFRS 18 replace IAS 1? IFRS 18 is mandatory for annual reporting periods beginning on or after 1 January 2027. Early adoption is permitted. IAS 1 remains in force until that date.
Is the operating profit subtotal in IFRS 18 the same as the one companies currently report? Not necessarily. IFRS 18 defines operating profit as the sum of items in the operating and investing categories. Many companies currently include interest income on cash or equity-method income above their operating profit line, which will move below it under IFRS 18. Expect the number to change even if the label stays the same.
What are management-defined performance measures under IFRS 18? MPMs are non-IFRS subtotals that management uses publicly to communicate financial performance. Adjusted EBITDA and underlying operating profit are common examples. IFRS 18 requires a formal reconciliation to the nearest IFRS subtotal in the notes to the financial statements.
Does IFRS 18 require restatement of prior periods? Yes. IFRS 18 applies retrospectively, so the comparative period in the first IFRS 18 financial statements must be restated to reflect the new categories, subtotals, and disclosures.
Does IFRS 18 affect the cash flow statement? IFRS 18 carries over most IAS 1 cash flow requirements with limited changes. The main impact is on classification consistency between the income statement and cash flow statement, particularly for entities with specified main business activities.
