She Moves $500,000 Into Municipal Bonds amid ‘Rare Opportunity’, Expecting Every Dollar of Interest to Stay Tax-Free. The IRS Counts That Interest When It Taxes Her Social Security, Pushing $16,900 More of Her Benefits Into Taxable Income

A 68-year-old hypothetical single retiree reads J.P. Morgan Private Bank’s October 19 analysis, which calls conditions in the municipal bond market a rare opportunity. She moves $500,000 into munis, a windfall from an inheritance she was not expecting.

At a hypothetical 5% yield, that pays $25,000 a year. The money sits next to her $24,000 Social Security benefit and $20,000 pension.

She expects to keep every dollar of that interest. The interest is exempt from federal income tax. The IRS still counts it, though, when it determines how much of her Social Security gets taxed. In her case, that moves $16,900 of benefits that used to be tax-free into taxable income.

Why Tax-Free Interest Still Counts Against Your Benefits

IRS Publication 915 tells retirees to compare a base amount with half their benefits plus “all your other income, including tax-exempt interest.” Planners call that total combined income.

A single filer has two trigger points: $25,000 and $34,000. Once combined income passes the first, half of each extra dollar starts making benefits taxable. Past the second, the share goes to 85%^[1], and total taxable benefits top out at 85% of what she collects.

Neither threshold rises with inflation. Each cost-of-living raise, such as the 3.6%^[2] increase coming in 2027, pushes more retirees past these lines.

Her Numbers Before and After the Bonds

Without the bonds, she takes half of her benefit, $12,000, and adds her pension. That gives a combined income of $32,000. Half of the amount above $25,000 is taxable, which comes to $3,500.

Add the muni interest and her combined income rises to $57,000, well past $34,000. Her taxable benefits run straight into the ceiling: $20,400, or 85% of her benefit.

That adds $16,900 to her taxable income. What she actually pays depends on the tax bracket where it lands.

What This Does to Her Real Tax Bill

For 2026, a single filer gets a $16,100 standard deduction. People 65 and older also get a $2,050 standard deduction and a new deduction of up to $6,000, which applies in full while modified adjusted gross income stays under $75,000.

Without the bonds, those deductions wipe out her $23,500 in adjusted gross income, leaving her with no federal income tax.

With the bonds, her taxable income increases to $16,250. That covers the 10% bracket, which runs to $12,400, and part of the 12% bracket.

The bill is near $1,702.

Her “tax-free” $25,000 really clears about $23,298.

How Munis Compare With Taxable Bonds in a 12% Bracket

A five-year Treasury yields 5%, or $24,900 a year on the same money. Treasury interest also counts toward combined income, so her benefits would still hit the $20,400 cap.

She would also owe about $2,988 on the interest itself, leaving $21,912. The munis still come out ahead.

In a 12% bracket, a 5% muni matches a taxable yield of about 5.7%, which is above every point on today’s Treasury curve.

That 5% is an example, and nothing guarantees it. Bond prices fall when rates rise, and the 10-year Treasury yield went from about 4.9% to above 5.1% in a single week this month. Credit quality varies by issuer, and selling before maturity can lock in a loss.

Medicare also counts muni interest when it sets premium surcharges. Her roughly $65,400 sits well below the 2026 $109,000^[3] threshold for single filers.

Run Two Tax Returns Before Moving the Money

Before buying, she should figure her Social Security taxes twice: once with the muni interest and once without it. Then she should compare her total federal tax and after-tax income against a taxable option such as Treasuries or CDs. If she plans only for the interest itself, the cost to her benefits shows up as a surprise in April. Some retirees respond by selling bonds after rates have risen, and that is a mistake they can rarely reverse.

Municipal bonds can still be a good fit for her. A different pension amount, filing status, or state tax situation can change the result, so it pays to run these numbers with her own figures.

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