Bond Amortization Schedule Singapore: How Premium and Discount Bonds Adjust Their Value Over Time
Why a bond bought above or below face value doesn’t hold that gap steady until maturity.
Last updated: September 2026
A bond amortization schedule is a table showing how the difference between a bond’s purchase price and its face value is gradually written down over the bond’s life. It applies to bonds bought at a premium, above face value, or a discount, below face value, and affects both accounting treatment and reported yield.
Not financial advice. All figures for educational reference only. Data as at September 2026.
Key Takeaways
- Amortization schedules apply whenever a bond is bought at a price different from its face value, whether at a premium or a discount.
- For a premium bond, amortization gradually reduces the recorded value down to face value by maturity, effectively spreading the extra cost paid across the holding period.
- For a discount bond, the equivalent process is called accretion, where the recorded value gradually rises to face value by maturity.
- Retail investors buying and holding individual bonds like Singapore Savings Bonds do not need to calculate this manually, since the mechanics matter most for accounting, tax reporting, and yield-to-maturity calculations.
- Understanding amortization helps explain why a bond’s yield-to-maturity differs from its stated coupon rate when the purchase price is not exactly at par.
What Is Bond Amortization Schedule?
When a bond is issued, it has a face value, also called par value, which is the amount the issuer repays at maturity. Bonds do not always trade at exactly this face value in the secondary market. Prevailing interest rates, credit conditions, and time to maturity all push bond prices above or below par.
A bond bought above its face value is bought at a premium. A bond bought below its face value is bought at a discount. In either case, the investor’s actual cost basis differs from the amount they will eventually receive back at maturity, and amortization is the accounting mechanism that reconciles this difference over the bond’s remaining life.
For a premium bond, amortization writes down the excess paid in small increments each period until the recorded value equals face value exactly at maturity. For a discount bond, the opposite process, called accretion, gradually increases the recorded value from the discounted purchase price up to face value.
This matters most directly for institutional investors, bond funds, and for individual investors filing taxes on bond income, since amortization or accretion affects how interest income and capital gain or loss are recognised over time rather than all at once at maturity.
The concept applies across bond types, including SGS bonds, corporate bonds, and even Singapore Savings Bonds if bought in the secondary market at a price other than par, though the vast majority of SSB holders buy at issuance and hold to redemption, where this mechanic has limited practical relevance.
How Does Bond Amortization Schedule Work in Singapore?
Two common methods exist for calculating amortization: the straight-line method, which spreads the premium or discount evenly across each remaining period, and the effective interest method, which ties the adjustment to the bond’s yield and produces a curve that changes more in later periods than earlier ones.
Under the effective interest method, which is the more commonly used and more accurate approach, the amount of premium amortized or discount accreted each period is calculated as the difference between the coupon payment received and the interest income implied by the bond’s yield to maturity applied to its current carrying value.
Over time, as the carrying value moves closer to face value, the gap between the coupon payment and the yield-implied interest income narrows, which is why the amortization amount typically changes period to period rather than staying constant, except under the simpler straight-line method.
| Scenario | Purchase Price vs Face Value | Adjustment Direction |
|---|---|---|
| Premium bond | Above face value | Carrying value decreases to face value (amortization) |
| Discount bond | Below face value | Carrying value increases to face value (accretion) |
| Par bond | Equal to face value | No adjustment needed |
Source: Standard bond accounting treatment, compiled for educational reference, 2026.
Bond Amortization Schedule Example
An investor buys a Singapore corporate bond with a S$1,000 face value and a 5-year maturity for S$1,050, a S$50 premium, because the bond’s 4% coupon is attractive relative to prevailing market yields at the time of purchase.
Under the effective interest method, the S$50 premium is amortized down over the 5 years, with a slightly larger portion written down in later years as the bond approaches maturity. By the final year, the bond’s carrying value has been reduced from S$1,050 back down to exactly S$1,000.
At maturity, the investor receives S$1,000, the face value, plus the final coupon payment. The S$50 premium they paid upfront has effectively been recovered through the amortization process reducing their taxable interest income each year, rather than showing up as a single capital loss at maturity.
Advantages
- More accurate income reporting. Amortization spreads the premium or discount adjustment across the holding period, giving a more accurate picture of true economic income each year rather than a distorted lump sum at maturity.
- Explains the gap between coupon rate and yield to maturity. Understanding amortization clarifies why a bond’s stated coupon rate and its actual yield to maturity differ whenever the purchase price is not exactly at par.
- Standard, well-established accounting method. The effective interest method is a recognised accounting standard, giving investors and institutions a consistent, comparable way to treat premium and discount bonds.
- Useful for tax planning on bond portfolios. Investors holding bond portfolios, particularly through funds or for tax reporting purposes, benefit from understanding how amortization affects reportable interest income year to year.
Risks and Limitations
- Complexity for individual investors. The calculations behind amortization schedules, particularly under the effective interest method, are not something most retail investors need to compute manually, and misunderstanding them can lead to confusion about actual returns.
- Does not apply uniformly across products. Bonds bought and held to maturity through certain retail products, like Singapore Savings Bonds bought at issuance, generally do not involve premium or discount amortization since they are typically bought at close to par.
- Tax treatment can vary by jurisdiction and product type. How amortization or accretion is treated for tax purposes is not always straightforward and can depend on the specific bond structure and applicable tax rules.
- Easy to conflate with market price changes. Amortization schedules track accounting carrying value, not the bond’s actual market price, which can fluctuate independently due to interest rate and credit movements.
Bond Amortization vs Bond Accretion Singapore
Amortization and accretion describe the same underlying concept, adjusting a bond’s carrying value toward face value, but apply in opposite directions depending on whether the bond was bought above or below par.
| Feature | Amortization (Premium Bond) | Accretion (Discount Bond) |
|---|---|---|
| Starting position | Purchase price above face value | Purchase price below face value |
| Direction of adjustment | Carrying value decreases over time | Carrying value increases over time |
| Effect on reported interest income | Reduces reported income below the coupon rate | Increases reported income above the coupon rate |
| End state at maturity | Carrying value equals face value | Carrying value equals face value |
The Bottom Line
A bond amortization schedule reconciles the gap between what you paid and what you will receive at maturity, spreading that difference across the holding period rather than recognising it all at once.
For most individual investors buying and holding retail products like Singapore Savings Bonds close to par, this mechanic matters less in practice, but it becomes relevant whenever a bond is bought meaningfully above or below face value in the secondary market.