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What’s a bond’s tax-equivalent yield?

Introduction to Bond’s Tax-Equivalent Yield

To appreciate bond investing strategies, beginners or even experienced traders and investors in the bond market must understand a core concept called the tax-equivalent yield. This term refers to the taxable yield that a tax-free bond must attain to equal a tax-free yield.

Tax-equivalent yield is crucial because it contributes to the comparison between taxable and tax-exempt investments. Notably, municipal bonds and treasury bonds differ; municipal bonds are usually free from federal income tax, while treasury bonds attract such taxes. As an investor, understanding the tax-equivalent yield can aid optimal decision-making when choosing between these investment options.

Calculation of Tax-Equivalent Yield

Formula of Tax-Equivalent Yield

Known as pre-tax yield, tax-equivalent yield (TEY) uses a relatively straightforward formula:

TEY = Tax-free yield / (1 – Tax rate)

Firstly, an investor identifies the tax rate applicable to their income bracket and their available tax-exempt yield. Then, these values help to calculate the tax-equivalent yield.

An Example of Tax-Equivalent Yield Calculation

Consider an investor subject to a federal income tax of 24% who wishes to invest in a municipal bond yielding 4%.

The tax-equivalent yield would be 4% / (1 – 0.24) which equates to a 5.26% tax-equivalent yield.

This means that a taxable bond would need to yield at least 5.26% to generate equivalent post-tax income as the exempt municipal bond with a 4% rate. If the taxable bond returns less than this figure, the municipal bond would be a more promising investment and vice versa.

Implication of Tax-Equivalent Yield in Advanced Trading Strategy

Familiarization with tax-equivalent yield is crucial for advanced bond market traders because it profoundly impacts the decision-making process when choosing between taxable and non-taxable bonds.

Experienced investors tenaciously seek opportunities to maximize returns whilst lowering tax liabilities. Tax-equivalent yield ramps up precision in this process. It allows investors to gauge whether their preferred taxable bond genuinely provides a higher return given their tax obligations.

For instance, a high-yield corporate bond might appear enticing due to its nominal yield. However, upon calculating the tax-equivalent yield, an investor might find that the municipal bond is a better proposition due to the tax savings.

Limits of Tax-Equivalent Yield

Limitations in Effectiveness

However, it’s crucial to recognize that the tax-equivalent yield is not an end-all tool. Other factors can influence an investment’s appeal. For example, the bond’s duration, issuer’s creditworthiness, liquidity, and interest rate risk are variables that can sway investing decisions. Moreover, local and state taxes, which are not accounted for in the basic TEY formula, can also affect the final outcome.

Accuracy for High-Income Investors

An additional limitation is that the formula assumes the marginal tax rate is constant. This is often not the case, especially for high-income investors, facing a progressive tax structure. The marginal tax rate rises as income level increases, ultimately distorting the accuracy of the TEY calculations.


The tax-equivalent yield concept is a powerful tool for comparing taxable bonds to tax-exempt ones like municipal bonds. It offers a common ground to make clear comparisons, factoring in an investor’s tax profile. However, like all tools, it has limitations and should not replace thorough risk assessment and evaluation of a bond’s other inherent characteristics. Even so, it serves as a fundamental principle for both beginners and advanced bond investors to make more informed and tax-efficient decisions.