85% of Your Social Security Can Be Taxed and Most Retirees Never See It Coming

"Combined income is your adjusted gross income, plus any tax-exempt interest (such as municipal bond interest), plus 50% of your annual Social Security benefit. That sum is the only figure that matters. The IRS thresholds that apply to it have not changed since 1984. For single filers, up to 50% of benefits become taxable once combined income exceeds $25,000, and up to 85% become taxable above $34,000."

"Because these thresholds are frozen while benefits rise with inflation each year, more retirees cross them automatically. The Consumer Price Index has climbed from 319.785 in March 2025 to 326.588 by January 2026, a steady upward drift that pushes nominal Social Security payments higher without any corresponding adjustment to the tax thresholds. Your benefit grows, the threshold stays fixed, and more of your income becomes taxable without Congress doing anything."

"With the 10-year Treasury yield currently at 4.09%, retirees holding CDs, bonds, or Treasury securities are earning meaningfully more interest than they did a few years ago. That interest flows directly into the combined income calculation. A retiree with $200,000 in a CD ladder earning 4% would add roughly $8,000 in interest income to their combined income total, potentially crossing a threshold they would otherwise have stayed under."

Combined income is the critical metric determining Social Security taxation, calculated as adjusted gross income plus tax-exempt interest plus half of annual Social Security benefits. IRS thresholds for single filers are $25,000 and $34,000, while married couples filing jointly face thresholds at $32,000 and $44,000. These thresholds have remained unchanged since 1984, creating an automatic bracket creep as Social Security benefits increase annually with inflation while tax thresholds stay fixed. Investment income, particularly from CDs, bonds, and Treasury securities earning current yields around 4%, significantly impacts combined income calculations. A retiree with $200,000 in CDs earning 4% adds approximately $8,000 in interest income, potentially triggering higher taxation of benefits without any congressional action.

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