Picture a retired couple: $40,000 a year in Social Security, plus $23,500 drawn from an IRA. Half their Social Security benefit is $20,000, and adding the IRA money puts their provisional income at $43,500. That is $500 below the $44,000 line for married couples filing jointly. They were in the clear.
Then the 2.8% COLA for 2026 added $1,120 a year to their benefit. Their provisional income rose to $44,060. They spent nothing more, earned nothing more, and crossed the line anyway. Up to 85% of their benefits can now be taxed instead of up to 50%. That is the mechanism most retirees never hear about until it shows up on their return.
The three-part formula behind the surprise
The IRS does not simply look at your Social Security check. It computes what it calls provisional income: your adjusted gross income, plus any tax-exempt interest, plus half of your annual Social Security benefits. Then it compares that number to thresholds that have been frozen in place for decades.
| Filing status | Up to 50% taxable above | Up to 85% taxable above |
|---|---|---|
| Single | $25,000 | $34,000 |
| Married filing jointly | $32,000 | $44,000 |
The 50% tier dates to 1984, the 85% tier to 1993, and neither has ever been adjusted for inflation. Your benefit compounds upward every year with the COLA while the tax lines stay exactly where Congress left them. Every raise quietly pushes more retirees, and more of each retiree's benefit, into taxable territory. It is the only major part of the tax code I know of where the income being taxed is indexed for inflation but the thresholds on it are not.
What "up to 85% taxable" actually means
This phrase causes more panic than it should, so let me deflate it. It does not mean the IRS takes 85% of your check. It means up to 85% of your benefits can be counted as taxable income, and that portion is taxed at your ordinary income tax rate, 10% to 37% depending on the rest of your income. The IRS worksheet phases this in gradually, so edging $60 over a threshold does not detonate your return. It does, however, start the clock on a slow bleed: each future COLA adds to provisional income and drags a bit more of your benefit into the taxable column.
Retirees with substantial outside income sit closest to the danger zone. If you take regular IRA withdrawals, have a pension, or earn part-time wages, you were probably near a threshold already, and the COLA just did the nudging. People living mainly on Social Security alone are rarely affected.
The one lever that helps: watch the threshold before January
You cannot control the COLA, but you can control the other half of the formula. Provisional income counts your AGI, so the timing and source of your other income matter. Drawing living expenses from a Roth IRA instead of a traditional IRA keeps money out of the formula entirely. If you are 73 or older and taking required minimum distributions, a qualified charitable distribution sent directly from the IRA to a charity satisfies the RMD without entering your AGI at all.
There is also a blunt, practical option: voluntary withholding. Social Security lets you withhold 7%, 10%, 12%, or 22% from each check with Form W-4V. It does not reduce your tax, but it smooths the bill across the year so you are not scrambling in April. And for tax years 2025 through 2028, taxpayers 65 and older get an extra $6,000 senior deduction ($12,000 for couples where both qualify), which softens the blow a little.
One honest caveat: I am describing the math, not giving tax advice. Run your own provisional income with last year's numbers before the next COLA lands. The historical figures on the free COLA dataset make the trend easy to see: every COLA since 1975 in one table, with the compound growth that explains why so many people who were safely below the thresholds in 2000 are not today.
Open the free COLA history tool and CSV download
Frequently asked questions
Does a Social Security COLA automatically raise my taxes?
Not automatically. A COLA raises your provisional income, which the IRS uses to decide how much of your benefits are taxable. Crossing a threshold means more of your benefits become taxable, but the formula is graduated, so a small crossing does not create a huge bill.
What is provisional income?
Your adjusted gross income plus any tax-exempt interest plus half of your annual Social Security benefits. The IRS compares it to fixed thresholds: $25,000 and $34,000 for single filers, $32,000 and $44,000 for joint filers.
How much of my Social Security benefits can be taxed?
Up to 50% in the middle tier and up to 85% in the top tier. That means up to 85% of your benefits can be included in taxable income and taxed at your ordinary rate, not that the IRS takes 85% of your check.
Do states tax Social Security benefits too?
Most states exempt them entirely. A handful still tax benefits, sometimes with income-based exemptions. State rules change often, so check your own state's current treatment.
Can I have federal taxes withheld from my Social Security check?
Yes, at 7%, 10%, 12%, or 22% through Form W-4V. If a COLA pushed you over a threshold, withholding a flat percentage avoids an April surprise.
Sources: IRS Publication 915 (Social Security and Equivalent Railroad Retirement Benefits); Social Security Administration benefit taxation guidance; The Senior Citizens League COLA estimates. Figures verified October 2026.