Should you own muni bonds? Tax-equivalent yield in 60 seconds

By Tom, CPA · Updated October 27, 2026

Part of: Easy Tax Strategies

TL;DR: Divide the muni yield by (1 minus your tax rate) to get its tax-equivalent yield, then compare with a taxable bond. Munis tend to win for investors in the 32% bracket and above, sometimes at 24%, especially for in-state bonds in high-tax states. They rarely make sense inside an IRA or for low-bracket investors.

Educational only, not tax, legal, or investment advice. Examples are illustrations, not predictions. Rules and limits change; verify current figures and talk to a qualified professional about your situation.

Municipal bonds are the tax code's way of saying "please fund the sewer system." In exchange, interest on most state and local government bonds is excluded from federal income tax. Whether that makes them a good deal for you is a one-line formula, and yet people buy them for the wrong reasons constantly: retirees in the 12% bracket, IRA holders who are already tax-sheltered, and anyone who hears "tax-free" and stops listening.

This guide gives you the 60-second math. Brackets are 2026 figures from IRS Rev. Proc. 2025-32, checked October 27, 2026. Part of easy tax strategies.

CPA Warning Label: Tax-exempt interest is not invisible: it counts toward Social Security taxation and ACA subsidy income, and some private activity bond interest is an AMT preference item.

Formula

Tax-equivalent yield = muni yield ÷ (1 − marginal tax rate)

That is the yield a taxable bond must pay to leave you with the same after-tax income. Examples at a 3.0% muni yield:

High earners should add the 3.8% net investment income tax, which applies to taxable interest but not to tax-exempt interest. At 37% plus 3.8%, the divisor is 0.592, and 3.0% becomes 5.07%. See the NIIT guide.

State double tax-free

Most states exempt interest on their own municipal bonds and tax interest on other states' bonds. Treasury interest, meanwhile, is federally taxable but exempt from state tax. So the fair comparisons are:

• In-state muni vs. corporate bond: combined rate = federal + state × (1 − federal) if you itemize and deduct state tax, or roughly federal + state if you do not.
• In-state muni vs. Treasury: only the federal rate matters for the Treasury, so use federal plus state against the muni.
• Out-of-state muni: federal exemption only; you owe state tax on the interest.

Check your state revenue department for its treatment; a handful of states have no income tax, which makes in-state bonds less special. See state income tax planning.

Bracket thresholds

2026 taxable income where the higher federal brackets begin:

The NIIT applies to the lesser of net investment income or modified AGI above $200,000 single or $250,000 joint; those thresholds are set by statute and are not indexed. Remember that your bond interest itself may push part of your income into the next bracket, so use the rate on the last dollars, not your average rate.

Example

Illustration: A married couple in 2026 has $500,000 of taxable income (32% bracket), modified AGI well above $250,000 (so the 3.8% NIIT applies), and lives in a state with a 5% income tax that exempts its own munis. They are choosing between:

• An in-state muni fund yielding 3.2%.
• A corporate bond fund yielding 4.8%.

Assume they take the standard deduction (so no federal benefit from state tax), and combine rates simply: 32% + 3.8% + 5% = 40.8%.

Tax-equivalent yield of the muni: 3.2% ÷ (1 − 0.408) = 5.41%, comfortably above 4.8%. The muni wins by $358.40 a year per $100,000. Same couple in the 22% bracket with no NIIT: combined 27%, TEY 4.38%, and the corporate fund wins.

A second example: the 24% bracket

Illustration: A single filer in 2026 has $150,000 of taxable income (24% bracket), lives in a state with a 6% income tax, takes the standard deduction, and is below the NIIT threshold. Options: an in-state muni yielding 3.0%, a Treasury yielding 4.2%, or a corporate bond yielding 4.8%.

• Muni after tax: 3.0%.
• Treasury after tax: 4.2% × (1 − 0.24) = 3.19% (no state tax).
• Corporate after tax: 4.8% × (1 − 0.30) = 3.36%.

Here the corporate bond edges out, the Treasury is close, and the muni comes last. At 24%, it really can go either way, which is why you run the numbers rather than trusting a rule of thumb.

Now bump the same single filer up to $300,000 of taxable income, which lands in the 35% bracket, and assume modified AGI is above the $200,000 NIIT threshold. Same three choices. Muni after tax: still 3.0%, since it owes no federal tax, no NIIT and no tax to its home state. Treasury after tax: the federal rate plus NIIT is 38.8%, so 4.2% × (1 − 0.388) = 2.57%. Corporate after tax: 35% + 3.8% + 6% = 44.8%, so 4.8% × (1 − 0.448) = 2.65%. The muni now wins by about a third of a percentage point, or roughly $350 a year per $100,000 compared with the corporate fund. Same bonds, same yields, different winner. The only thing that changed was the bracket, which is the whole point of doing the sixty-second math instead of picking whatever your brother-in-law owns.

When not to

• Inside an IRA or 401(k). The account already shelters the interest, and withdrawals are taxed as ordinary income anyway. Munis there waste their only advantage.
• Low brackets. At 10% or 12%, taxable bonds almost always win.
• Social Security recipients near the taxation thresholds. Tax-exempt interest is included in provisional income, so it can make more of your benefits taxable.
• ACA premium tax credit recipients. Tax-exempt interest counts in the MAGI used for subsidies; see munis for early retirees.
• AMT exposure. Interest on certain private activity bonds is a preference item for the alternative minimum tax.
• Credit and concentration risk. Single-state funds concentrate economic risk in one place. Individual bonds need diversification; see bond funds vs. individual bonds.

Tax quirks to know

• Capital gains are taxable. Only the interest is exempt. Selling a muni or muni fund at a gain is a taxable capital gain.
• Market discount. Buying a muni below its face value can create ordinary income at maturity under the market discount rules, with a de minimis exception for small discounts.
• Reporting. Tax-exempt interest is still reported on your return (Form 1040 line 2a), on Form 1099-INT box 8 or 1099-DIV box 12.
• Fund distributions may include some taxable income or gains; check the year-end tax statement.

Funds vs. individual bonds vs. Treasuries

Once the math favors munis, you still have to pick a vehicle:

For residents of high-tax states in the 24% bracket, Treasuries are often the overlooked middle option: no state tax, and the federal hit is moderate. Run the formula for both.

Common myths

• "Munis are risk-free." Defaults are rare among highly rated issuers, but they happen, and muni prices fall when rates rise, just like other bonds.
• "Tax-free means it doesn't show up on my return." It does, on line 2a, and it affects Social Security and ACA calculations.
• "A higher yield muni is always better." Higher yields usually mean longer maturities, lower credit quality or call risk.
• "Munis are only for the rich." Mostly true, but in-state bonds can help upper-middle earners in high-tax states.

Lavish Larry once bought a muni fund for his IRA because a newsletter said "tax-free." His IRA now holds a tax-free bond inside a tax-deferred account that will be taxed as ordinary income on withdrawal. That is the financial equivalent of wearing a raincoat in the shower.

Sixty-second checklist

1. Find your marginal federal rate, plus NIIT if over the threshold, plus state rate.
2. Divide the muni yield by (1 minus that combined rate).
3. Compare with a taxable bond of similar maturity and credit quality.
4. Check Social Security, ACA and AMT side effects.
5. Only hold munis in taxable accounts.

And a reminder that a tax-free yield is not a free lunch on risk: the muni market has its own credit and liquidity quirks. Compare apples to apples, and keep a skeptical eye on anything sold mostly on the words "tax-free," much like the fine print in churning math.

Bottom line

Munis are a high-bracket tool, held in taxable accounts, and chosen by formula rather than by the warm feeling the phrase tax-free produces. Run the sixty-second math every time yields change.