Key points
- Transaction costs, fees, premiums and discounts are spread across the instrument's expected life rather than recognised upfront.
- A bond purchased at €97 per €100 nominal accretes to par through the income statement, not only at maturity.
- We've seen the EIR challenged most often when entities exclude fees or origination costs from the initial yield computation (sometimes by 10 to 30 basis points per instrument).
- For credit-impaired assets in Stage 3, the entity applies the EIR to amortised cost net of the loss allowance ( IFRS 9.5 .4.1(b)).
Why the EIR trips up audit teams
On about half the financial instrument files we review, the EIR schedule is wrong. Not dramatically wrong (the rate itself is usually close) but wrong because one or two fees were left out of the initial yield computation. A €20,000 broker commission excluded from a €5M bond changes the rate by roughly 15 basis points. That is small on a single instrument and invisible in the P&L on day one. Across a lending portfolio, it compounds into a misstatement that sits in interest income for years.
IFRS 9 .B5.4.1 defines the effective interest rate as the rate that exactly discounts estimated future cash payments or receipts through the expected life of the financial instrument to the gross carrying amount at initial recognition. Every contractual term matters: fixed or floating coupon, call options, prepayment features, and all fees integral to the instrument's yield. IFRS 9 .B5.4.1 explicitly requires inclusion of origination fees paid or received between the parties.
On each reporting date the entity multiplies the opening gross carrying amount by the EIR and recognises the result as interest income (or expense). Whatever gap exists between that calculated amount and the cash coupon received (or paid) adjusts the carrying amount. This is how a discount or premium amortises over time.
When a financial asset moves to Stage 3 (credit-impaired), the entity applies the EIR to the amortised cost (gross carrying amount minus the loss allowance) rather than to the gross carrying amount. ISA 540.13 (a) requires us to evaluate whether the entity's method for this calculation is appropriate. That means ticking and bashing the arithmetic, yes, but also confirming the switch from gross to net basis happened at the right point.
Worked example: Hoffmann Maschinenbau GmbH
Client: German engineering company, FY2025, revenue €28M, HGB reporter also preparing IFRS consolidated accounts. Hoffmann holds a €5M corporate bond purchased on 1 January 2024 at €4,850,000. The bond carries a 3% annual coupon (€150,000 per year) and matures on 31 December 2028. Transaction costs of €20,000 were paid at acquisition.
Step 1: determine the initial carrying amount
Purchase price €4,850,000 plus transaction costs €20,000 = €4,870,000 gross carrying amount at initial recognition.
Step 2: calculate the EIR
We need the rate that discounts five annual cash flows of €150,000 plus the €5,000,000 redemption at maturity back to €4,870,000. Solving iteratively produces an EIR of approximately 3.575%.
Step 3: recognise Year 1 interest income
Interest income for FY2024 = €4,870,000 x 3.575% = €174,103 (rounded). Cash coupon received = €150,000. That €24,103 difference increases the carrying amount to €4,894,103 at 31 December 2024.
Step 4: recognise Year 2 interest income
Interest income for FY2025 = €4,894,103 x 3.575% = €174,964. Cash coupon = €150,000. Carrying amount rises to €4,919,067 at 31 December 2025.
By maturity the amortised cost schedule converges on par (€5,000,000). The €130,000 discount plus €20,000 in transaction costs flow through the income statement as part of interest income across five years rather than appearing as a lump at redemption. The file should tell a story of steady accretion, and the approach is defensible because the EIR was calculated at inception using all contractual cash flows and integral costs.
Common engagement issues
Teams frequently exclude origination fees or broker commissions from the EIR calculation, treating them as period costs in the income statement instead. IFRS 9 .B5.4.1 requires all fees integral to the instrument's yield to be included in the EIR computation. Excluding them overstates income in the first period and understates it in every period after that.
When an asset transitions to Stage 3, the interest income calculation must switch from the gross carrying amount to the amortised cost (net of the loss allowance) under IFRS 9.5 .4.1(b). Entities that continue applying the EIR to the gross amount overstate interest income on impaired instruments. It is genuinely frustrating how often we see this missed, because the absolute amounts involved look small relative to total interest revenue and nobody flags it until the file review.
EIR method vs. straight-line amortisation
| Dimension | Effective interest rate method | Straight-line amortisation |
|---|---|---|
| Interest pattern | Constant rate on the carrying amount; income amount changes each period | Constant monetary amount each period |
| IFRS requirement | Mandatory under IFRS 9 for all amortised-cost instruments | Not permitted under IFRS 9 ; allowed under some local GAAPs as a simplification |
| Accuracy for deep discounts | Reflects compounding; higher precision when the premium or discount is large | Acceptable only when the difference from EIR is immaterial |
| Typical engagement issue | Fee exclusion from the EIR; switch to net basis for Stage 3 assets | Entity uses straight-line under IFRS when the EIR method is required |
In practice the distinction matters when the instrument carries a significant premium or discount, or when origination fees are involved. For a bond purchased at par with no transaction costs, both methods produce the same result.
Related terms
Related reading
Frequently asked questions
Does the effective interest rate change during the life of a fixed-rate instrument?
For a fixed-rate instrument measured at amortised cost, the EIR is locked at initial recognition and does not change unless the instrument is modified. IFRS 9.B5.4.5 permits recalculation only when the entity revises estimates of payments or receipts (excluding changes in expected credit losses). A floating-rate instrument recalculates the EIR when the benchmark rate resets, reflecting the variable cash flows over the remaining term.
How do I audit the effective interest rate calculation?
Recalculate the EIR independently using the instrument's contractual cash flows, purchase price, and all fees integral to the yield (IFRS 9.B5.4.1). Compare the entity's carrying amount schedule to your recalculation at each reporting date. The most common error is an omitted fee that changes the rate by 10 to 30 basis points, small enough to pass unnoticed on a single instrument but material across a portfolio.
What happens when a loan is modified but not derecognised?
IFRS 9.5.4.3 requires the entity to recalculate the gross carrying amount by discounting the modified contractual cash flows at the original EIR, then recognise the resulting gain or loss in profit or loss. The original EIR stays. The carrying amount resets. Auditors should verify the entity did not substitute a new market rate for the original EIR when performing this calculation.