Municipal Bonds for High-Income Investors: 2026 Tax-Equivalent Yield Calculator
A 4% muni bond doesn't yield 4% to you — it yields the equivalent of a taxable bond paying 6.25% if you're in a 36% combined bracket. Most millionaires with taxable accounts have never run this math precisely. Here's how to do it, including the NIIT factor most calculators miss.
The core logic: compare after-tax yields
Municipal bond interest is exempt from federal income tax under IRC § 103, a rule in place since 1954 and unaffected by any recent legislation including OBBBA (July 2025).1 A muni bond paying 4% delivers 4% after federal tax. A Treasury or corporate bond paying 4% delivers significantly less — how much less depends on your bracket.
The tax-equivalent yield (TEY) answers the question: what pretax yield does a taxable bond need to match a muni bond on an after-tax basis?
TEY = Muni Yield ÷ (1 − Your Combined Marginal Rate)
- At 24% marginal rate: 4% muni → TEY of 5.26%
- At 32% + NIIT (35.8% combined): 4% muni → TEY of 6.23%
- At 35% + NIIT (38.8% combined): 4% muni → TEY of 6.54%
The math tilts further in munis' favor the higher your bracket — which is exactly why they exist.
Tax-Equivalent Yield Calculator — 2026
Enter your income and the muni yield you're considering. Optionally enter a taxable bond yield to compare directly.
Uses 2026 federal income tax brackets (IRS Rev. Proc. 2025-32) and standard deduction ($32,200 MFJ / $16,100 single). NIIT rate 3.8% per IRC § 1411; threshold $200,000 single / $250,000 MFJ (not inflation-adjusted). Municipal bond interest excluded from NIIT base per IRS Topic 559. Does not account for state income tax, AMT, or itemized deductions.
The NIIT multiplier: the factor most calculators miss
If your MAGI exceeds $200,000 (single) or $250,000 (married filing jointly), you owe 3.8% net investment income tax (NIIT) on your investment income above that threshold.2 Taxable bond interest — Treasuries, corporate bonds, CDs — is net investment income and fully subject to the NIIT.
Municipal bond interest is explicitly excluded from both the NIIT base and from MAGI for NIIT purposes.2 Munis don't just avoid income tax — they sidestep the 3.8% NIIT surcharge entirely.
For a married investor in the 32% bracket with MAGI above $250,000, the effective marginal rate on taxable bond income is 35.8% (32% + 3.8%). A 4% muni's TEY at 35.8% combined: 4% ÷ 0.642 = 6.23%. Most investment-grade Treasuries and corporates don't approach that level — which means a lower-yielding muni can outperform a higher-yielding taxable bond after the IRS takes its cut.
The private activity bond (PAB) AMT trap
Not all muni interest is treated identically. Interest from private activity bonds (PABs) — munis issued to fund private-sector projects like airports, stadiums, and affordable housing — is exempt from regular income tax under § 103, but is an AMT preference item under IRC § 57(a)(5).3 If your alternative minimum taxable income (AMTI) exceeds the AMT exemption, you may owe AMT on PAB interest you assumed was tax-free.
2026 AMT exemption amounts (OBBBA, P.L. 119-21):4
- Single: $90,100 — phaseout begins at $500,000 AMTI at a 50% rate
- Married filing jointly: $140,200 — phaseout begins at $1,000,000 AMTI at a 50% rate
For most $1M–$5M investors without large ISO exercises or other preference items, the OBBBA's expanded exemptions put AMT exposure well outside the normal range. But if you're regularly exercising ISOs, running a large S-corp, or holding PAB-heavy muni funds, confirm your AMT exposure before assuming full tax exemption on PAB interest.
How to identify PABs: Individual bonds are labeled in your brokerage bond screener (look for "AMT" or "private activity" in the bond description). For muni ETFs and mutual funds, the fund prospectus and annual report disclose the PAB percentage. National muni funds typically hold more PABs than state-specific funds; the yield premium on PABs reflects this AMT risk.
In-state vs. out-of-state munis: the state-tax double exemption
Most states exempt interest from their own municipal bonds from state income tax while taxing out-of-state muni interest. In high-income-tax states — California (13.3% top marginal rate), New York (10.9%), New Jersey (10.75%), Minnesota (9.85%) — holding in-state munis adds a meaningful second layer of tax exemption.
Adding state tax to the TEY formula: TEY = Muni Yield ÷ (1 − Federal Rate − State Rate − NIIT if applicable). A California resident in the 32% federal bracket above the NIIT threshold: 4% ÷ (1 − 0.32 − 0.038 − 0.133) = 4% ÷ 0.509 = 7.86%. The market prices this in — California muni yields run materially lower than national muni yields, reflecting the triple-exemption advantage for California residents.
State tax modeling is outside this calculator's scope. For high-state-tax residents, the in-state vs. national muni tradeoff warrants a fee-only advisor who can model your complete tax picture.
Individual bonds vs. muni ETFs vs. muni mutual funds
| Format | Effective min. | Pros | Cons |
|---|---|---|---|
| Individual bonds | ~$100K+ to ladder | Known maturity/yield, no fund fees, hold-to-maturity eliminates duration risk, individual TLH opportunities | Illiquid, bid-ask spread, minimum diversification requires $300K–$500K+ |
| Muni ETFs (MUB, VTEB, HYD) | Any amount | Highly liquid, low cost (0.06–0.07% ER), instant diversification, easy TLH between funds | NAV fluctuates with rates, duration risk visible in daily price swings |
| Muni mutual funds | $1,000+ | Active management, laddered average maturity, state-specific options | Higher expense ratios (0.25–0.50%), potential for year-end capital gain distributions that are taxable |
For $1M–$5M investors: a core position in low-cost muni ETFs (liquidity, immediate diversification) combined with a ladder of individual bonds in your highest-conviction state is a common structure. A fee-only advisor with fixed-income expertise can size the ladder to your time horizon and cash-flow needs.
Duration risk: rising rates hurt long bonds
Bond prices move inversely to interest rates. A muni fund with a 7-year duration loses approximately 7% in market value for every 1% rise in rates. Short-duration munis (1–3 year) carry minimal price sensitivity; long-duration munis (10–20+ years) offer higher yields but meaningful rate risk.
For taxable-account munis used as a bond substitute, matching duration to your time horizon reduces forced selling at a loss. Holding individual bonds to maturity eliminates duration risk entirely — you get par back regardless of what rates do in between.
Credit risk: GO bonds vs. revenue bonds
General obligation (GO) bonds are backed by the full taxing power of the issuer — the municipality can raise taxes to service the debt. Revenue bonds are backed only by a specific revenue stream (tolls, water and sewer fees, hospital revenues) and typically offer higher yields to compensate for narrower backing.
Investment-grade munis (AAA–BBB) have extremely low historical default rates. Moody's long-run data shows 10-year cumulative default rates below 0.1% for investment-grade municipal bonds. Below-investment-grade ("high yield") munis can generate attractive TEYs but carry meaningfully higher default risk — appropriate only as a deliberate allocation with eyes open, not as a yield-chase substitute for investment-grade bonds.
When munis don't make sense
- Inside an IRA, 401(k), or Roth: The federal tax exemption is wasted in a tax-deferred or tax-free account. Taxable bonds belong in these accounts; munis in the taxable account. See asset location.
- Low marginal brackets (below 22%): Below 22%, taxable Treasuries almost always offer better after-tax yields than comparable munis. The yield discount munis accept for their tax advantage isn't justified.
- AMT-heavy situations: If you consistently pay AMT due to ISOs or other preference items, PABs convert from tax-exempt to taxable for AMT purposes. Screen for non-PAB munis or use state-specific funds with low PAB exposure.
- Very short time horizons (under 1 year): A high-yield savings account or T-bill is simpler and often competitive. Muni ETF bid-ask and price risk aren't worth it for cash you'll need in months.
The fee-only advisor perspective
A commission-based broker has little incentive to steer you toward munis — munis carry lower gross yields, and the tax benefit accrues entirely to you rather than generating spread income. A fee-only fiduciary, paid on your assets or a flat fee, is motivated purely by after-tax return.
For $1M–$5M investors optimizing a taxable account, the muni vs. taxable decision intersects your marginal rate, state tax profile, NIIT exposure, AMT status, Roth conversion strategy (which affects MAGI), and TLH opportunities within the bond allocation. Getting the fixed-income piece right is worth several basis points per year — on $500,000 of taxable-account bond exposure, the difference between the right and wrong structure can easily exceed $3,000–$5,000 annually in after-tax yield.