Municipal Bond Calculator

Municipal bonds, debt issued by states, cities, and other local authorities, are prized for one feature: their interest is usually exempt from federal income tax, and from state tax too if you live where the bond was issued. That exemption makes a muni's modest headline yield more valuable than it looks, especially for investors in high tax brackets.

For a general look at how compounding builds a balance over time, outside of bonds specifically, try our compound interest calculator.

This calculator finds a muni's yield to maturity and translates it into a tax-equivalent yield, so you can compare it directly against taxable bonds on an after-tax basis.

How does this calculator work?

Enter the bond's par value, market price, years to maturity, and annual coupon rate, along with your federal tax bracket and state tax rate.

The calculator finds the bond's yield to maturity and its tax-equivalent yield: the return a taxable bond would need to match this muni once taxes are considered.

Because municipal bond interest is usually exempt from federal (and sometimes state) tax, the tax-equivalent yield shows its real value compared with taxable bonds, especially in higher brackets.

Worked example

Consider a $10,000 muni priced at par, with a 3.5% coupon and 15 years to maturity, held by an investor in a 32% federal bracket with a 6% state tax (also exempt).

Yield to maturity

3.500%

Combined tax rate (fed + state)

38%

Tax-equivalent yield

5.645%

Comparable taxable bond at 5.0%

loses to the muni

How the numbers work

The tax-equivalent yield is the muni's yield divided by one minus your combined tax rate: 3.5% ÷ (1 − 0.38) = 3.5% ÷ 0.62 = 5.645%.

In other words, a taxable bond would have to yield 5.645% to leave this investor with the same after-tax income the 3.5% muni delivers. A 5.0% taxable bond falls short, so the muni is the better deal at this tax rate.

For this investor, the 3.5% tax-free muni works like a 5.645% taxable bond. A taxable corporate bond would need to yield more than 5.645% to come out ahead after taxes, so a 5% taxable bond is actually the inferior choice here.

The benefit scales with your tax bracket: the same muni is far less compelling for someone in a low bracket, where the exemption is worth little.

When munis make sense

Municipal bonds shine for high-bracket investors holding bonds in taxable accounts, where the federal (and possibly state) exemption translates into a meaningfully higher after-tax yield. They make little sense inside a tax-advantaged account like an IRA, where you'd be giving up yield for a tax break you don't need. And in low brackets, a higher-yielding taxable bond often wins outright.

Two cautions: the interest is exempt, but capital gains from selling a muni before maturity are still taxable, and some munis can trigger the alternative minimum tax. Credit quality varies by issuer, so the exemption isn't the only thing to weigh.