Amortizable Bond Premium: Definition, Calculation, and Examples


Amortizable bond premium, often referred to as the bond premium amortization, is a crucial tax concept. It relates to the excess amount paid for a bond beyond its face value. This premium can be tax-deductible and is spread out (amortized) over the bond’s lifetime. In this article, we will delve into the definition, calculation, and tax implications of amortizable bond premiums, providing you with a comprehensive understanding of this essential financial concept.

Amortizable bond premiums are a fundamental part of the world of finance, providing investors with unique opportunities to manage their tax liabilities effectively. In this comprehensive guide, we’ll explore the concept in depth, covering essential topics such as the reasons behind bond premiums, their tax advantages, and the constant yield method for amortization.

Amortizable bond premium

An amortizable bond premium is a tax term that refers to the excess price paid for a bond over and above its face value. Depending on the type of bond, the premium can be tax-deductible and amortized over the life of the bond on a pro-rata basis.

Bond premiums

Bond premiums often arise when market interest rates decrease, causing the price of a bond to increase in the secondary market. This means that the bond is sold at a premium to its face value. The difference between the bond’s current price (or carrying value) and its face value represents the premium of the bond.

For example, if a bond with a face value of $1,000 is sold for $1,050, it has a $50 premium. Over time, as the bond approaches its maturity date, the value of the bond gradually decreases until it reaches its par value. This process is known as amortization.

Cost basis and tax benefits

For bond investors, the premium paid for a bond is an important component of the bond’s cost basis. This is particularly significant for tax purposes. If the bond generates taxable interest, the bondholder has the option to amortize the premium. In other words, a portion of the premium can be used to reduce the amount of interest income included in their tax calculations.

Investors in taxable premium bonds often find this advantageous, as the amortization can offset the interest income, effectively reducing the taxable income generated by the bond. Consequently, this results in a lower income tax liability. Each year, the cost basis of the taxable bond is reduced by the amount of premium amortized.

Tax-exempt bonds

In the case of bonds that pay tax-exempt interest, the bond investor must still amortize the bond premium. However, it’s essential to note that this amortized amount is not deductible in determining taxable income. Instead, the taxpayer must reduce their basis in the bond by the amount of amortization for the year.

The constant yield method

The Internal Revenue Service (IRS) requires the use of the constant yield method to amortize a bond premium every year. This method is essential for determining the bond premium amortization for each accrual period.

Calculating premium amortization

The constant yield method calculates premium amortization by multiplying the adjusted basis by the yield at issuance and then subtracting the coupon interest. This can be expressed in formula form as follows:

Accrual = Purchase basis x (Yield to Maturity / Accrual periods per year) – Coupon interest

The first step in this process is determining the yield to maturity (YTM), which is the discount rate equating the present value of all remaining bond payments to the bond’s basis.

Let’s illustrate this with an example:

Suppose an investor purchases a bond for $10,150 with a five-year maturity, a par value of $10,000, a 5% coupon rate paid semi-annually, and a yield to maturity of 3.5%.

In the first period, the yield used to amortize the bond premium is 3.5% divided by 2 (since it’s a semi-annual bond), which equals 1.75%. The coupon payment per period is 5% divided by 2, multiplied by $10,000, which equals $250. The amortization for the first period is calculated as follows:

Accrual for period 1 = ($10,150 x 1.75%) – $250

Accrual for period 1 = $177.63 – $250

Accrual for period 1 = -$72.38

For the second period, the bond’s basis is adjusted. It becomes the purchase price minus the accrual in the first period: $10,150 – $72.38 = $10,077.62. Therefore, the amortization for the second period is:

Accrual for period 2 = ($10,077.62 x 1.75%) – $250

Accrual for period 2 = $176.36 – $250

Accrual for period 2 = -$73.64

This process continues for the remaining periods, ultimately bringing the bond’s basis to par value upon maturity.

Maximizing tax benefits

Investors looking to optimize their tax strategies should consider the tax implications of bond premiums. By effectively managing these premiums, investors can significantly reduce their taxable income and, consequently, their tax liabilities.

Tailoring strategies to bond types

Different bonds, such as taxable and tax-exempt bonds, require different approaches to premium amortization. Understanding the specifics of each bond type is crucial for maximizing tax benefits.

Strategic bond investments

Investors can strategically invest in bonds to make the most of premium amortization. Decisions regarding bond purchases and holding periods can impact the overall tax benefits.


Understanding amortizable bond premiums is essential for investors looking to optimize their tax strategies. By effectively managing bond premiums, investors can reduce their taxable income and, consequently, their tax liabilities. The constant yield method provides a standardized approach to calculating premium amortization, ensuring consistency and compliance with IRS requirements.

Frequently Asked Questions

What is an amortizable bond premium?

An amortizable bond premium refers to the excess amount paid for a bond over and above its face value. It’s a tax term that can have implications for bond investors, especially when it comes to managing their tax liabilities.

Why do bond premiums occur?

Bond premiums often arise when market interest rates decrease. This leads to the price of a bond increasing in the secondary market, causing it to be sold at a premium compared to its face value.

How does amortizing the premium benefit investors?

Amortizing the premium can be advantageous for investors because it allows them to offset the interest income generated by the bond. This reduction in taxable income can result in lower income tax liability for the bondholder.

What is the constant yield method, and why is it important?

The constant yield method is a standardized approach required by the Internal Revenue Service (IRS) to calculate bond premium amortization. It’s crucial because it ensures compliance with IRS regulations, providing consistency in the way premium amortization is determined.

Are there different strategies for taxable and tax-exempt bonds?

Yes, different strategies are required for taxable and tax-exempt bonds when it comes to premium amortization. It’s important for investors to understand the specifics of each bond type to maximize their tax benefits effectively.

Key takeaways

  • Amortizable bond premiums are the excess amounts paid for a bond over its face value, often resulting from declining market interest rates.
  • Amortizing bond premiums can offset interest income, reducing overall taxable income for investors.
  • The constant yield method is used to calculate premium amortization, ensuring compliance with IRS regulations.
View Article Sources
  1. 26 CFR § 1.171-2 – Amortization of bond premium– legal information institute
  2. 26 CFR § 1.171-2 – Amortization of bond premium – GOVinfo
  3. 26 CFR 1.171-4 — Election to amortize bond premium on – eCFR