Tax Equivalent Yield Calculator

How Tax-Equivalent Yield Compares Municipal and Taxable Bonds

Introduction to Tax-Equivalent Yield

Tax-equivalent yield is the bridge between a tax-free municipal bond and a taxable investment that has to survive federal and state income tax. A bond with a lower headline yield can still deliver more spendable income if the tax bill on the alternative is high enough. This calculator turns that comparison into one break-even number so you can see what a taxable bond, bond fund, or CD would need to earn to match the municipal income after taxes.

That comparison matters because municipal bond quotes are usually stated before tax, while taxable bonds are usually quoted the same way. The calculator asks for the municipal yield, your marginal federal bracket, your marginal state bracket, and the yield on the taxable investment you want to benchmark. From those inputs it estimates the taxable yield that leaves you with the same after-tax income and shows how the taxable side compares once taxes are applied.

For investors who hold bonds in taxable brokerage accounts, the result can be a useful filter. A municipal bond that looks ordinary on a quote screen may be more attractive than it first appears, while a taxable bond that looks superior on yield alone may lose some of that edge after taxes. The calculator is not trying to pick the winner for you; it is trying to isolate the tax effect so the rest of your analysis starts from a clearer baseline.

How to Use the Tax-Equivalent Yield Calculator

Using the tax-equivalent yield calculator is straightforward once you decide how the municipal bond should be taxed in your comparison.

Enter the municipal bond yield first, then your marginal federal rate and marginal state rate. Those percentages should reflect the tax rate that applies to the next dollar of ordinary interest, not your overall average tax burden. Next, choose whether the municipal income is exempt from state tax or taxed by your state, and decide whether the state tax should be treated as federally deductible in your situation.

After you calculate, compare the break-even taxable yield with the yield on the bond or fund you are evaluating. If the taxable investment yields less than the tax-equivalent figure, the municipal bond is producing more after-tax income. If it yields more, the taxable investment may be ahead on income alone. That result is most useful as a first pass, before you factor in credit quality, call risk, duration, fees, and the type of account you are using.

Tax-Equivalent Yield Formula

The tax-equivalent yield formula starts with the share of taxable interest you keep after federal and state taxes:

combined tax rate = federal rate + state rate

If your state tax is deductible for the taxable comparison, the calculator reduces the state effect before it combines the rates. That assumption lowers the effective tax burden and therefore lowers the break-even taxable yield:

combined tax rate = federal rate + state rate × (1 - federal rate)

For municipal bonds that are still taxed by your state, the calculator first discounts the municipal yield by that state rate and then converts the remainder into a taxable equivalent. The general method is:

municipal after-tax yield = municipal yield × (1 - municipal state tax rate)

tax-equivalent yield = municipal after-tax yield / (1 - combined tax rate)

The older shortcut below is the deductible-state-tax version, not the right default for every household. Use the select box in the form to match the assumption you want to model. In MathML form, the deductible-state-tax combined rate is $t=t\_f+t\_s-t\_ft\_s$, where $t\_f$ and $t\_s$ represent the federal and state tax rates respectively. Use that version only when state tax deductibility is a reasonable assumption for the comparison you are making.

The tax-equivalent yield is then expressed through the following MathML equation:

Formula: TEY = r / (1 - t)

$\mathrm{TEY}=\frac{r}{1-t}$

Here, $r$ denotes the municipal bond's after-tax yield after any state tax on the municipal bond itself and $t$ is the combined tax rate. The denominator is the fraction of taxable interest you would keep after taxes. Dividing the municipal after-tax yield by that fraction scales it up to the taxable coupon needed to produce the same spendable income.

As a practical check, if you keep 63% of taxable interest, a 3.00% municipal yield has to be lifted to about 4.76% on the taxable side before the after-tax dollars line up. That is the basic logic behind every result the calculator shows.

Worked Example: A 3.00% In-State Municipal Bond

Suppose you are comparing an in-state municipal bond that yields 3.00%. Your marginal federal tax rate is 32%, and your marginal state tax rate is 5%. With the default non-deductible state-tax assumption, the taxable interest tax burden is 37.0%. That means you would keep 63.0% of the interest from a taxable bond after taxes.

The calculator then divides the municipal after-tax yield by the after-tax share of taxable income. In this case, 3.00% divided by 0.630 gives a tax-equivalent yield of about 4.76%. A taxable bond yielding 4.50% would still trail on an after-tax basis, while one yielding 5.10% would clear the hurdle if the two investments had similar risk and features.

Examples like this show why municipal bonds tend to look more competitive as tax rates rise. The higher your marginal bracket, the larger the gap between headline yield and spendable yield on taxable interest. That is why the same municipal bond can seem merely fair in one bracket and very strong in another.

The pattern is easy to see in the table: as taxes rise, the taxable bond needs to offer a higher coupon to keep up with the tax-free municipal bond. The result is a break-even rate, not a recommendation, but it gives you a clean threshold for comparing income investments on an after-tax basis.

Interpreting a Tax-Equivalent Yield Result

Treat the tax-equivalent yield as a break-even line, not a forecast. If the calculator returns 4.76%, it means a taxable investment needs to deliver about that much before tax to match the municipal bond after tax. A higher taxable yield may produce more income; a lower one may leave the municipal bond ahead.

That threshold can help with individual bond comparisons, bond fund screening, and account placement decisions. Municipal bonds often fit taxable brokerage accounts well because their tax advantage is valuable there. In tax-advantaged accounts such as an IRA or 401(k), the same tax-free feature often matters less because the account wrapper already changes the tax treatment.

The calculator focuses on yield, not total return. Credit quality, maturity, duration, call risk, and liquidity can all change the investment picture, so the break-even yield should be read as one important lens rather than the whole decision.

Limitations and Assumptions in Tax-Equivalent Yield

Like any tax-equivalent yield calculator, this one relies on simplified tax assumptions. It uses marginal federal and state rates, which is usually the right way to compare the next dollar of taxable interest, but real tax situations can involve AMT treatment, state-by-state exemption rules, or special municipal bond categories that do not fit a single flat rate.

The calculator also assumes that the taxable comparison is ordinary interest income. That works well for many bonds, CDs, and bond funds, but not every income-producing investment is taxed the same way. If you are comparing assets with unusual tax treatment, treat the result as a screening number rather than a final answer.

It does not measure investment risk. Two bonds with the same break-even yield can still have very different credit quality, duration, call features, liquidity, and fees. A higher taxable yield may simply be compensation for more risk, while a lower municipal yield may still make sense if the tax savings and credit profile are better.

Tax law and personal circumstances also change. A move to a different state, a shift in income, retirement, or new legislation can all change the comparison. Revisit the calculation whenever those inputs move, especially if you are deciding whether to buy new municipal income or keep a taxable bond in place.