On Oct. 14, the government will announce your 2027 Social Security raise. Every forecast I’ve seen puts it around 3.5%.
Here’s what nobody will announce that day: Your tax brackets won’t keep up. They’re on track to rise 3.2%. That gap looks tiny. It isn’t, because it happens every single year, and it was designed that way.
I’ve been a CPA since 1981 and I’ve written about money for more than 35 years. This is one of the sneakier things I’ve watched Congress do to retirees, and almost nobody knows it happened.
Two rulers measuring the same dollar
Your Social Security cost-of-living adjustment, or COLA, is set by one inflation gauge. Your tax brackets are set by another. They don’t agree, and the disagreement always breaks the same way.
Social Security uses the Consumer Price Index for Urban Wage Earners and Clerical Workers, or CPI-W. It compares the third quarter of this year with the third quarter of last year, and whatever it says, that’s your raise.
The IRS uses something called the chained CPI. It assumes that when steak gets expensive, you buy chicken. Because it builds in that substitution, it almost always shows less inflation than the regular index.
How much less? The Congressional Budget Office estimated the chained index runs about a quarter of a percentage point lower per year, on average. Last month’s numbers fit the pattern: CPI-W rose 3.5% over the past year; the chained index rose 3.3%.
What Congress did in 2017
Before 2018, your brackets and standard deduction rose with the regular CPI, same family of numbers as your Social Security raise. The Tax Cuts and Jobs Act changed that.
Tucked into the law was a switch to the chained CPI for indexing the brackets, the standard deduction and most other dollar figures in the tax code. The Tax Policy Center puts it plainly: “The change in indexing is permanent.”
That word matters. Most of the individual tax cuts in that law were written to expire. The slower inflation measure wasn’t. The lower rates got a sunset date. The slower creep didn’t.
It wasn’t an accident, either. Congress’s own scorekeeper, the Joint Committee on Taxation, counted the switch as raising $133.5 billion over 10 years.
You don’t raise $133 billion by accident. You raise it by pushing a little more of everyone’s income into higher brackets, year after year, without ever voting on a rate increase.
What it looks like for 2027
Bloomberg Tax ran the numbers Sept. 11. Its projection for 2027 is a 3.2% inflation adjustment, up from 2.7% for 2026. The IRS makes it official in October or November, but these projections are usually right on the money.
So, per Bloomberg, the standard deduction for a married couple goes from $32,200 this year to $33,200 next year. Single filers go from $16,100 to $16,600. The top of the 12% bracket for a couple moves from $100,800 to $104,050.
Meanwhile, The Senior Citizens League expects a 3.5% COLA, and AARP is at 3.6%. Your income rises faster than the lines that decide how it’s taxed.
One more wrinkle, and it’s a beauty. Because of last fall’s 43-day government shutdown, the Bureau of Labor Statistics never published October 2025 inflation data. Bloomberg notes the chained index for 2027 had to be computed on an 11-month average. Your brackets are being set with a month missing.
Why a quarter point is a big deal
A quarter of a percentage point sounds like nothing. Over a retirement, it isn’t.
Here’s my arithmetic. Compound a quarter point for 20 years and the gap grows to roughly 5%. For a couple, 5% of that $104,050 bracket ceiling is about $5,200 of income that lands in the 22% bracket instead of 12%.
That’s about $520 a year in extra tax, every year, and the gap keeps widening the longer you live. Nobody sent you a letter. No senator gave a speech. The ruler just got shorter.
And it stacks on top of an older problem I wrote about recently: the income thresholds that decide how much of your Social Security is taxed haven’t moved since the 1980s and 1990s. Those aren’t indexed slowly. They aren’t indexed at all.
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The new senior deduction has the same flaw
Last year’s tax law gave everyone 65 and older an extra $6,000 deduction, or $12,000 for a couple when both qualify. It phases out once income tops $75,000 for singles or $150,000 for couples, and it runs only through 2028.
Notice what’s missing. The IRS lists no inflation adjustment for it. It’s a flat $6,000 in 2025 and a flat $6,000 in 2028, no matter what your groceries cost by then. Then it disappears unless Congress acts.
Use it while you have it. Just don’t build a retirement plan around it.
What to do about it
You can’t change the index. You can change how you play it in three moves:
Use the 2027 numbers now. If you’re thinking about a Roth conversion or a big IRA withdrawal in December, the projected 2027 bracket edges tell you how much room you’ll have next year, too. Filling the 12% bracket to the line each year beats a big lump later.
Check your withholding before your raise lands. A 3.5% bump on your benefit check can nudge more of it into taxable territory. Form W-4V lets you have taxes withheld from Social Security so April doesn’t bite.
Know the other numbers that move. Milliman, a company that provides actuarial products and services, projects the 401(k) limit rising to $25,500 for 2027, with an $8,500 catch-up for workers 50 and older and $11,750 for ages 60 to 63. Those are estimates until the IRS speaks, but if you’re still working, plan for them.
Bottom line
One of the Social Security “fixes” floating around Washington would switch your COLA itself to the chained CPI. Retirees hate the idea, and they should.
But here’s what they should also know: Congress already did it to the other side of the ledger nine years ago. It just didn’t tell anyone.
Your raise arrives in January. A slice of it will be taxed a little harder than last year’s, and a little harder still the year after. Now you know why, and you know what to do about it.
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