She Bought Vanguard’s Bond ETF for Its 4.27% Tax-Free Yield but Could Owe More Tax on Her Social Security

For retirees looking to turn savings into steady income, bonds are getting another look. The Federal Reserve raised its target range to 3.75%–4% in September, and the 10-year Treasury yield has climbed above 5%. A bond fund promising tax-free income can look especially appealing.

Picture a single retiree who puts $300,000 into Vanguard Tax-Exempt Bond ETF (NYSEARCA:VTEB), drawn by its 4.27% annualized yield as of October 5. Its monthly payments vary, but suppose she receives $12,810 in federally tax-exempt income over a full year.

The catch tends to show up at tax time.

Tax-Free Interest Still Counts Toward Social Security Taxes

The IRS adds up one-half of your benefits plus all your other income, including tax-exempt interest to figure out whether your benefits are taxable. Social Security calls that total your combined income. Municipal bond interest stays off your tax bill, but it still counts in this formula.

For single filers, combined income between $25,000 and $34,000 makes up to 50% of benefits taxable. Above the upper line, up to 85% can be taxed.

For married couples filing jointly, the lines sit at $32,000 and $44,000. These thresholds have never been adjusted for inflation, so more retirees cross them every year.

How a Tax-Free Payment Can Make Benefits Taxable

Let’s give our retiree $30,000 a year in Social Security, plus $25,000 in fully taxable IRA withdrawals. Her combined income is half her benefit ($15,000) plus the IRA money, which comes to $40,000.

Because she’s already past $34,000, $9,600 of her benefits are taxable before she buys any bonds.

Now add the $12,810 of muni interest. Her taxable benefits jump to about $20,490, which puts roughly $10,890 more of her Social Security on her tax return. Above the upper threshold, most of each dollar of tax-free interest draws benefits into taxable income, up to the cap.

That share of her benefit counts as income, but her tax rate is still her bracket. If those extra dollars land in the 12% bracket, she owes about $1,307 more in federal tax. Her 4.27% tax-free yield works out to roughly 3.8% after that knock-on tax.

A Treasury Comparison Shows How Small the Gap Can Get

The five-year Treasury yields about 5%. Treasury interest is federally taxable, and in her case, each dollar also makes another 85 cents of Social Security taxable, until she reaches the cap.

Run $300,000 through both. Assuming a 5% Treasury yield and a 12% tax rate on all the added taxable income, the Treasury leaves about $11,670 after federal tax, and the muni fund leaves about $11,503. Treasury interest is also exempt from state income tax, which can widen that gap for people in high-tax states. Someone in the 22% bracket could see the muni come out ahead. The two bonds also carry different credit and maturity profiles, so yield is only part of the comparison.

Her combined income can climb even without a new investment. As of early October, the Senior Citizens League projects a 3.5% Social Security COLA for 2027. Bigger benefit checks and larger required IRA withdrawals can push more income over thresholds that never rise with inflation.

Run Your Own Numbers Before You Buy

The most useful step is a simple side-by-side. Take the fund’s actual recent distributions, which vary from month to month, add them to your combined income, and see how much more Social Security income becomes taxable. Then do the same for a taxable bond or CD. Whichever leaves more in your pocket after both taxes is your real yield.

Check the fund’s tax details too. Some muni income can be subject to state tax or the alternative minimum tax, and the fund’s share price can fall when rates rise.

Tax-free income is still valuable, especially for retirees whose combined income sits well below $25,000 or well above the point where 85% of benefits is already taxed. Your filing status, deductions, and state of residence all shift the math, so plug in your own figures, or ask a tax preparer to, before you move a large sum.

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