Tax Treatment of Bond Premium Amortization

Investors who purchase taxable bonds above par value can elect to amortize the bond premium—the excess paid over the bond’s maturity value—against interest income received each year. This amortization reduces ordinary income currently, adjusts the bond’s cost basis downward, and lowers the capital loss (or increases the capital gain) at maturity or sale.

Why bonds trade above par and create a premium

A bond may trade above par (its maturity value) for several reasons. If interest rates fall after a bond is issued, its existing coupon rate—the fixed annual yield printed on the bond—becomes more attractive than newly issued bonds with lower coupons. Investors bid up the price to secure that higher yield, driving the bond’s price above $100 per $100 of principal.

Alternatively, the issuer’s credit quality may have improved since issuance, making the bond safer and thus more valuable. Or the bond may carry special features—callability, convertibility, or liquidity advantages—that command a premium.

When an investor buys such a bond at, say, $1,050 for a $1,000 principal amount, the $50 difference is the bond premium. At maturity, the investor receives only $1,000, realizing a $50 capital loss. Without the amortization election, this loss is recognized in full in the year the bond matures or is sold—a concentrated deduction. With the election, the loss is spread over the bond’s remaining life, reducing interest income each year.

The mechanics of amortization

Under the tax treatment of bond premium amortization, the investor calculates how much of the premium should be allocated to each year using the constant-yield method (also called the effective interest method). This approach reflects how the bond’s intrinsic value accretes toward par as it approaches maturity.

The formula is:

Amortizable amount for the year = [Adjusted issue price at start of year × Yield to maturity] − Coupon payment

The adjusted issue price (AIP) is the original purchase price minus amortization claimed in prior years. As the AIP declines annually, less premium amortization is claimed each subsequent year—front-loading the deductions.

Example: Suppose an investor buys a 5-year, 4% coupon bond with a $1,000 maturity value for $1,050, purchased on January 1, year 1. The yield to maturity is 2.34%. The premium is $50.

• Year 1: AIP is $1,050. Amortizable amount = ($1,050 × 2.34%) − $40 (coupon) ≈ $24.57.
• Year 2: AIP is $1,050 − $24.57 = $1,025.43. Amortizable amount = ($1,025.43 × 2.34%) − $40 ≈ $24.00.
• And so on, declining each year until the full $50 premium is claimed.

After amortization is claimed, the investor reports interest income of only $40 − amortization. So in year 1, taxable interest would be $40 − $24.57 = $15.43 instead of the full $40 coupon.

Cost basis adjustment

The amortization election also reduces the investor’s cost basis in the bond by the amount of amortization claimed each year. This adjustment is critical for calculating gain or loss if the bond is sold before maturity.

Continuing the example: if the investor sells the bond after year 1 for $1,045, the adjusted cost basis is now $1,050 − $24.57 = $1,025.43. The gain on sale is $1,045 − $1,025.43 = $19.57, not $1,045 − $1,050 = −$5 (a loss). The amortization claimed has converted a potential loss into a gain.

Conversely, if the bond is held to maturity, the final sale price is $1,000, and the adjusted basis after all amortization has been claimed is $1,000 (par). The net result is zero gain or loss, with the premium loss “spread” across the years as interest income reductions rather than a lump-sum capital loss.

Election and revocation

The amortization election must be made on the investor’s tax return for the year in which the bond is purchased. It is made on a bond-by-bond basis, but once made, it applies to all substantially identical bonds held at the time of election. An investor cannot cherry-pick which similar bonds to amortize.

Critically, the election is permanent and cannot be revoked without IRS consent. This is why it is important to analyze whether amortization benefits the investor’s overall tax situation before making the election.

When amortization helps or hurts

Amortization is beneficial when:

• The investor is in a high tax bracket in the purchase year and expects to be in a lower bracket in future years. The front-loaded deductions are taken at a higher rate.
• The investor anticipates a large passive-loss carryover or expects to use the amortization deductions to offset other capital gains.
• The investor intends to hold the bond to maturity and would otherwise recognize the entire loss in a single year.

Amortization is unfavorable when:

• The investor expects to sell the bond significantly above par before maturity, converting what would have been a large capital gain into a smaller one.
• The investor is in a lower bracket now and expects to be in a higher bracket in the future (the deductions are taken at the lower rate).
• The investor can use the capital loss from the bond premium to offset capital gains in the purchase year, avoiding the need to spread deductions over time.

Interaction with passive-loss rules and at-risk limitations

Interest income from bonds is generally not subject to passive-loss limitations, even if the bond is held as part of a larger passive activity. However, if amortization reduces interest income, the deduction itself may be subject to passive-activity loss limitations if the bond is considered a passive investment in the context of a broader business or investment venture.

Similarly, an at-risk limitation under Section 465 does not typically apply to bond investments, since the investor’s capital at risk is plainly limited to the purchase price.

Municipal bonds and the exception

Municipal (tax-exempt) bonds are treated differently. If an investor buys a municipal bond at a premium, the premium is not amortizable. Instead, the premium is non-deductible and reduces the par value for purposes of calculating yield to maturity. This asymmetry reflects the fact that municipal bond interest is already exempt from federal income tax, so permitting amortization would be a double benefit.

Conversely, a municipal bond purchased at a discount (a loss position) may, in some cases, generate a capital gain at maturity that is taxable, as the bond accretes to par.

See also