Key Points
- Basic EPS uses only shares actually outstanding; diluted EPS adds the effect of all dilutive potential ordinary shares.
- Use basic EPS to report actual earnings allocation; use diluted EPS to show worst-case dilution if all instruments convert.
- IAS 33.66 requires both figures presented with equal prominence on the face of the income statement.
- A gap of more than 10% between basic and diluted EPS typically signals material dilution risk to investors.
Side-by-side comparison
| Dimension | Basic EPS (IAS 33.9–29) | Diluted EPS (IAS 33.30–63) |
|---|---|---|
| Denominator | Weighted average of ordinary shares actually outstanding during the period | Weighted average adjusted for incremental shares from dilutive options, warrants, and convertible instruments |
| Numerator | Profit or loss attributable to ordinary shareholders, after deducting preference dividends | Same starting point, plus add-back of after-tax interest on dilutive convertible debt |
| Treatment of share options | Ignored entirely | Included via the treasury stock method (IAS 33.45) if dilutive |
| Treatment of convertibles | Ignored entirely | Assumed converted from the start of the period; interest saved added to the numerator |
| Sequencing requirement | None | IAS 33.44 requires instruments ranked from most dilutive to least dilutive, included one at a time |
| When they equal each other | Always produces the baseline figure | Equals basic EPS when no dilutive potential ordinary shares exist |
Decision rule: Report basic EPS to show the earnings actually attributable to each outstanding share. Report diluted EPS alongside it to show investors the lowest earnings per share that would result if every dilutive instrument converted.
What is Basic EPS vs Diluted EPS?
The distinction bites when the entity has share-based payment arrangements or convertible debt outstanding. IAS 33.66 requires both figures on the face of the statement of profit or loss, not buried in the notes. If the engagement team audits only basic EPS and treats diluted EPS as a disclosure afterthought, it risks missing a material misstatement in per-share data that analysts use directly for valuation multiples.
The sequencing test under IAS 33.44 is where most errors occur. The standard requires the entity to rank each potentially dilutive instrument by its incremental effect on EPS (from most dilutive to least dilutive) and include them one at a time. If the next instrument increases EPS rather than decreasing it, the entity stops. Teams that skip the sequencing step and dump all instruments into the denominator simultaneously can include anti-dilutive instruments, which overstates diluted EPS and violates the standard. ISA 540.13(a) requires the auditor to evaluate whether the entity's method for the estimate is appropriate, and the sequencing test falls squarely within that evaluation.
Worked example
Client: Belgian holding company, FY2025, revenue €185M, IFRS reporter listed on Euronext Brussels. Groupe Lefevre reports net profit attributable to ordinary shareholders of €14.8M. The weighted average number of ordinary shares outstanding is 10,000,000. Groupe Lefevre has two potentially dilutive instruments: (a) 500,000 share options granted to executives with an exercise price of €20, and (b) €8M in convertible bonds carrying 4% annual interest, convertible into 600,000 ordinary shares. The average market price of Groupe Lefevre's shares during FY2025 is €32. The corporate tax rate is 25%.
Step 1 — Determine the numerator and denominator for basic EPS
Net profit attributable to ordinary shareholders is €14.8M. Groupe Lefevre has no preference shares outstanding, so no deduction applies. The weighted average share count is 10,000,000. Basic EPS is €14.8M divided by 10,000,000 = €1.48.
Documentation note: record the net profit per the audited statement of profit or loss, confirm the absence of preference shares from the share register, and cross-reference the weighted average share count to the IAS 33.19 reconciliation.
Step 2 — Apply the treasury stock method to the share options
The 500,000 options at €20 would generate notional proceeds of €10M. At the average market price of €32, Groupe Lefevre could notionally repurchase 312,500 shares (€10M / €32). Incremental shares entering the denominator: 500,000 minus 312,500 = 187,500. No numerator adjustment arises for options.
Documentation note: record the exercise price per the share option agreement, the average market price source (Euronext Brussels daily closing prices), the notional proceeds, the buyback calculation per IAS 33.45, and the incremental share count of 187,500.
Step 3 — Adjust for the convertible bonds
Annual interest avoided on conversion is €320,000 (4% of €8M). After-tax saving is €240,000 (€320,000 multiplied by 0.75). The denominator increases by 600,000 shares.
Documentation note: record the bond coupon rate, the nominal amount, the tax rate applied, and the number of shares issuable per the bond agreement. Verify the conversion ratio against the prospectus per IAS 33.33–34.
Step 4 — Rank instruments and calculate diluted EPS
The share options produce incremental EPS of €0 / 187,500 shares = €0.00 per incremental share (most dilutive). The convertible bonds produce €240,000 / 600,000 shares = €0.40 per incremental share (less dilutive). Options enter first.
After options: EPS = €14.8M / 10,187,500 = €1.4528.
After convertible bonds: EPS = (€14.8M + €0.24M) / 10,787,500 = €1.3942.
The convertible bonds remain dilutive (€1.3942 is below €1.4528), so both instruments are included. Diluted EPS is €1.39.
Documentation note: record the sequencing test per IAS 33.44, the diluted EPS at each inclusion step, and the conclusion that both instruments pass the dilution test. If the bonds had increased EPS above €1.4528, exclude them and document the anti-dilution conclusion.
Conclusion: basic EPS of €1.48 and diluted EPS of €1.39 are both defensible. If the team had skipped the sequencing test and included both instruments simultaneously, it would have arrived at the same diluted EPS by coincidence in this case. On an engagement with anti-dilutive instruments mixed in, that shortcut would produce a misstated figure.
Why it matters in practice
Teams frequently present diluted EPS only in the notes rather than on the face of the statement of profit or loss. IAS 33.66 requires both basic and diluted EPS to appear with equal prominence on the face of the income statement for each class of ordinary shares. Burying diluted EPS in a note violates the presentation requirement and creates a qualification risk under ISA 705.
The treasury stock method under IAS 33.45 requires the average market price for the period as the buyback price. Teams that substitute the year-end closing price produce an incorrect incremental share count. In periods of high share price volatility, the error can shift diluted EPS by several cents per share, enough to affect analyst consensus comparisons.
Related terms
Frequently asked questions
What is the difference between basic EPS and diluted EPS?
Basic EPS reflects earnings attributable to ordinary shares actually outstanding. Diluted EPS adjusts both the numerator and denominator to show the lowest earnings per share that would result if all dilutive potential ordinary shares (options, warrants, convertible bonds) converted. IAS 33.66 requires both figures on the face of the income statement.
Can diluted EPS be higher than basic EPS?
No. If every potentially dilutive instrument turns out to be anti-dilutive after applying the IAS 33.44 sequencing test, the entity reports diluted EPS equal to basic EPS (IAS 33.41). Diluted EPS can never exceed basic EPS because the standard excludes anti-dilutive instruments from the calculation entirely.
Does the basic-vs-diluted distinction apply to interim reports?
Yes. IAS 33.4 requires entities that present EPS to calculate both figures for every period for which a statement of profit or loss is presented. Under IAS 34, that includes interim periods. The weighted average share count and the average market price for the treasury stock method are calculated for the interim period, not annualised from the full year.