How municipal bonds work
When you buy a municipal bond, you lend money to a state, city, county, school district or public authority. In return you receive interest, usually twice a year, and your principal back on the maturity date, which may be decades away. Many munis can be called, or repaid early, at the issuer’s option, typically after interest rates fall.
The SEC describes two major types. General obligation bonds are not tied to a single project: some are backed by property or other taxes, and others by the issuer’s general funds, its full faith and credit. Revenue bonds are repaid from a specific source, such as tolls, water fees or the payments of a conduit borrower like a nonprofit hospital or college. Some revenue bonds are non-recourse: if that revenue dries up, bondholders have no claim against the conduit borrower.
You can buy individual munis through a broker or own them through a mutual fund or ETF that holds many issues. Each offering has an official statement describing the bonds and their risks, and issuers post updates on EMMA, the free disclosure website of the Municipal Securities Rulemaking Board. Like other Bonds, munis fall in price when interest rates rise.
How municipal bond interest is taxed
Section 103 of the tax code excludes interest on state and local bonds from gross income, with exceptions. Interest on private activity bonds that are not qualified bonds is taxable, as is interest on arbitrage bonds, most federally guaranteed issues sold after 1983 and certain tax credit bonds, such as Build America Bonds. Tax-exempt interest still goes on your return, on Form 1040, line 2a.
Interest on qualified private activity bonds issued after August 7, 1986 is generally a preference item for the alternative minimum tax, shown in box 9 of Form 1099-INT or box 13 of Form 1099-DIV.
State tax depends on where you live. Most states with an income tax exempt interest on their own bonds and tax bonds from other states; when the Supreme Court upheld that practice in 2008, 41 states used it. Bonds of U.S. territories, such as Puerto Rico, can also be exempt from state and local tax. A bond free of federal, state and local tax for its local buyers is often called triple tax-free.
The exemption covers interest only. A gain when you sell a bond or fund shares for more than you paid is a capital gain, market discount on a bond bought below face value is generally taxed as ordinary income, and a muni fund’s capital gain distributions are taxed even though its interest dividends are not.
Tax-exempt interest still counts toward income tests
Municipal interest escapes federal income tax, but it does not vanish from your finances. Several rules that set taxes and benefits start from modified adjusted gross income or a similar measure and add tax-exempt interest back in, which can surprise retirees who moved into munis to lower their income. Before shifting a large bond allocation into munis, check how the interest interacts with these rules, one of which works in your favor:
- Social Security: provisional income, which decides how much of your benefit is taxable, adds all tax-exempt interest to half your benefits and your other income, and can feed the tax torpedo.
- Medicare: IRMAA surcharges on Part B and Part D premiums use AGI plus tax-exempt interest, from your tax return two years earlier.
- Marketplace coverage: income for the premium tax credit includes tax-exempt interest. For 2026 coverage, the credit ends above 400% of the federal poverty line.
- Net investment income tax: tax-exempt interest is not net investment income, so it avoids the 3.8% tax that taxable interest can owe above $200,000 of modified AGI single or $250,000 joint.
- Borrowing: you can’t deduct interest on money borrowed to buy tax-exempt bonds, or shares of a fund that pays only exempt-interest dividends.
Tax-equivalent yield: comparing munis with taxable bonds
Because of the tax break, municipal bonds usually pay lower interest than taxable bonds of similar quality and maturity. To compare them fairly, convert the muni’s yield into the taxable yield that would leave you the same after tax, its tax-equivalent yield, using the formula below.
The higher your marginal tax rate, the more a muni’s yield is worth. In the 12% or 22% bracket, a taxable bond often leaves more after tax. In the 32%, 35% or 37% bracket, munis often come out ahead, especially in-state bonds in a high-tax state and for high earners who would also owe the 3.8% net investment income tax on taxable interest. Treasury interest sits in between: federally taxable but exempt from state and local income tax.
The comparison also decides where munis belong. Their only edge is the tax exemption, so they fit a taxable account rather than an IRA or 401(k). For bond money that must sit in a taxable account, munis are one of the main ways to cut tax drag; choosing which account holds which bonds is asset location.
Risks of municipal bonds
Munis have a reputation for safety, and many are high quality, but they are not risk-free, and unlike bank deposits they carry no FDIC insurance. The SEC urges investors to read the official statement rather than rely on a label such as general obligation or on a credit rating, which is usually paid for by the issuer and can change after you buy. A diversified fund spreads credit risk across many issuers but brings its own price swings and fees. The main risks:
- Credit risk: the issuer or conduit borrower may pay late or not at all. Default rates vary with the type of bond and who ultimately repays it, and speculative projects carry more risk.
- Interest rate risk: prices fall when rates rise, more so for long maturities.
- Call risk: the issuer may repay early when rates drop, leaving you to reinvest at lower yields.
- Inflation risk: fixed interest payments buy less as prices rise.
- Liquidity risk: many individual munis trade infrequently, so selling before maturity may mean accepting a lower price.
- Bracket risk: the exemption is worth less if your tax rate falls later, for example in retirement.
Illustrative numbers
$100,000 in a 3.5% municipal bond vs. a 4.8% taxable bond (illustrative yields)
- Municipal yield
- The muni’s yield to maturity, or a fund’s yield
- Marginal tax rate
- Your rate on the next dollar of interest: federal, plus state if the bond is also state-exempt, plus 3.8% if the NIIT applies
Compare with taxable bonds of similar credit quality and maturity; the simple formula ignores AMT and state deduction interactions.
Municipal bond interest, free of federal tax$3,500
Taxable bond interest before tax$4,800
Taxable bond after tax, 24% bracket$3,648: the taxable bond wins
Taxable bond after tax, 32% bracket$3,264: the muni wins
Muni’s tax-equivalent yield at 24% / 32%4.61% / 5.15%
The break-even federal rate here is about 27%: 1 − 3.5 ÷ 4.8 = 27.1%. Below it the taxable bond leaves more after tax; above it the muni does. State tax on the taxable bond, or the 3.8% NIIT for high earners, lowers the break-even. The yields are examples, not current market rates.
At a glance
How bond interest is taxed, by type of bond (federal rules in 2026)
| Bond | Federal income tax | State income tax | 3.8% NIIT |
|---|---|---|---|
| In-state municipal bond | Exempt, but reported on your return | Usually exempt | No |
| Out-of-state municipal bond | Exempt, but reported on your return | Usually taxed | No |
| Qualified private activity bond | Exempt, but may count for AMT | Depends on the state | No |
| Taxable municipal bond | Taxed | Depends on the state | Yes, above the threshold |
| U.S. Treasury bond | Taxed | Exempt | Yes, above the threshold |
| Corporate bond | Taxed | Taxed | Yes, above the threshold |
Put it in your plan
Municipal Bonds in MoneyWhatIf
When you give an account a bond allocation in MoneyWhatIf, you can split it among up to four bond types, including own-state municipal, exempt from federal and state tax in the model, and national municipal, federal-exempt but state-taxable. The type sets how that share’s interest is taxed in a taxable account. Exempt interest still enters the modeled Social Security provisional-income, IRMAA and marketplace-income calculations, and it stays outside the NIIT. Every bond type uses the plan’s bond return assumption, so a municipal type does not lower the yield; set that assumption to fit the bonds you hold.
Common questions
Municipal Bonds FAQs
Are municipal bonds completely tax-free?
Not always. The interest is generally free of federal income tax, but your state may tax it if the bond comes from another state, and some private activity bond interest counts for the alternative minimum tax. Gains when you sell, taxable market discount and a fund’s capital gain distributions are all taxed, and the interest still counts in income tests for Social Security, Medicare premiums and marketplace coverage.
Should I hold municipal bonds in an IRA or 401(k)?
Generally no. Inside a retirement account the interest is already sheltered, so a muni’s tax exemption adds nothing while its lower yield still costs you. Withdrawals from a traditional IRA or 401(k) are taxed as ordinary income no matter what the account held. A taxable bond with a higher yield usually fits a retirement account better, and munis fit a taxable account.
Are municipal bonds a good investment for retirees?
Only for some. Many retirees are in the 12% or 22% bracket, where a taxable bond or Treasury often leaves more after tax, and muni interest still counts in the income tests for taxing Social Security and for Medicare surcharges. Munis tend to suit retirees with high incomes, large taxable accounts and a state income tax on other bond interest. Compare after-tax yields at the rate you expect to pay in retirement, not the one you paid while working.
Are municipal bond funds tax-exempt?
Their interest dividends are. A muni fund passes its tax-exempt interest to you as exempt-interest dividends, reported in box 12 of Form 1099-DIV, with any AMT portion in box 13. But the fund’s capital gain distributions are taxable, and so is any gain when you sell fund shares. State tax depends on how much of the fund holds your own state’s bonds.