On October 14, the Social Security Administration announced that benefits will rise 3.6% in 2027. That’s the biggest cost-of-living adjustment in four years, up from 2.8% for 2026, and it works out to about $75 more a month for the average retired worker.
Most coverage stops at the headline number. But the way that number gets made is oddly specific, and once you see it, a few things about your benefits start to make more sense: why the raise sometimes lags what you’re paying at the store, why some years there’s no raise at all, and why the check you actually get in January might be smaller than the COLA suggests.
The formula is written into law
Social Security’s annual raise isn’t decided by Congress each year, and it isn’t a judgment call by anyone at SSA. Legislation in the early 1970s set up an automatic trigger, and the first automatic COLA was paid in 1975. Before that, benefit increases needed their own act of Congress.
Today the formula sits in section 215(i) of the Social Security Act. It compares an inflation index across two specific three-month windows, and whatever the math produces, rounded to the nearest tenth of a percent, becomes the COLA.
Which inflation number SSA uses
The index is the CPI-W, the Consumer Price Index for Urban Wage Earners and Clerical Workers, published monthly by the Bureau of Labor Statistics. It’s a cousin of the more famous CPI-U that you see in news headlines, but it’s weighted toward the spending patterns of working households.
That detail matters, because retirees don’t spend like working households. They tend to spend more of their budget on health care and housing and less on things like commuting. Whether the CPI-W undercounts retirees’ real inflation is a long-running argument, and alternatives like an elderly-focused index or a “chained” CPI come up regularly. AARP notes that switching to chained CPI would cut the COLA by about 0.3 percentage points a year on average, which is why it tends to get pushback.
The three months that count
Here’s the part most people don’t know. SSA doesn’t look at inflation over the whole year. It looks only at July, August, and September.
The agency averages the CPI-W for those three months in the current year, then compares that to the same three-month average from the last year a COLA took effect. For 2027, the actual figures from SSA’s Office of the Chief Actuary look like this. In 2025, the CPI-W read 316.349 in July, 317.306 in August, and 318.139 in September, for an average of 317.265. In 2026, the same months came in at 327.104, 328.481, and 330.654, for an average of 328.746.
The math is just the percentage change between those two averages: 328.746 minus 317.265, divided by 317.265. That comes out to about 3.62%, which rounds to 3.6%.
So the raise you’ll live on for all of 2027 was set by prices during a single summer quarter of 2026. If inflation spikes in, say, November, it won’t show up in your benefit until the following year’s calculation. That built-in lag is a big part of why the COLA can feel behind. It’s always catching up to last summer.
Year-over-year inflation was also running hot through that window. According to AARP, the CPI-W was up 3.4% in July, 3.5% in August, and 3.9% in September compared with a year earlier.
Why some years there’s no raise
The law only triggers a COLA if that third-quarter average goes up. If the rounded increase is zero, or if prices fall, there’s simply no COLA. Benefits don’t get cut when the index drops, but they don’t move either.
That’s happened three times: 2010, 2011, and 2016. Anyone who was retired then remembers it, because a zero COLA year usually lands right when people are most worried about money.
What the 3.6% looks like in real dollars
SSA’s 2027 COLA fact sheet estimates the average retired worker’s monthly benefit will rise from $2,095 to $2,170. An aged couple where both receive benefits goes from $3,238 to $3,355. The average disabled worker goes from $1,642 to $1,701, and an aged widow or widower living alone goes from $1,936 to $2,005.
A few other numbers move automatically along with the COLA. Supplemental Security Income rises from $994 to $1,029 a month for an individual and from $1,491 to $1,544 for a couple. The maximum benefit for someone retiring at full retirement age goes from $4,152 to $4,188 a month. And if you’re working while collecting before full retirement age, the earnings test limit rises from $24,480 to $25,560 a year.
Workers feel one change too. The maximum amount of earnings subject to Social Security tax goes from $184,500 to $192,300.
When the money actually shows up
The timing is a little confusing. The COLA technically applies to December benefits, but because Social Security pays in arrears, December’s benefit is paid in January. So the first bigger deposit in your checking account arrives in January 2027.
SSI works differently. SSA says the higher SSI payments start going out on December 31, 2026, for about 7.3 million people.
If you want the exact figure early, SSA says notices will be viewable online in your my Social Security account starting in late November, up to three weeks before paper notices arrive by mail in December. To get the online version, you need an account and need to opt into paperless notices by November 18. This year’s notice is a simplified one-page version with exact dates and dollar amounts. Details are in the SSA’s announcement.
Why your check might grow by less than 3.6%
For most retirees on Medicare, the Part B premium comes straight out of their Social Security payment. When that premium rises, it eats part of the COLA before the money ever reaches your account.
AARP reports the standard Part B premium is projected to rise $6.60 in 2027, to $209.50. SSA says the official 2027 premium amount will appear in the my Social Security Message Center starting in late November. On an average benefit, a $6.60 premium increase would take a modest bite out of a $75 raise, but for people with smaller benefits, the share is bigger.
There’s a safety net here called the hold-harmless provision. It keeps many beneficiaries’ net Social Security payment from dropping year over year because of a Part B premium increase. According to the Congressional Research Service, it mattered most in low-COLA years: roughly 70% of beneficiaries were protected in 2016 and 2017, when the COLA was 0% and 0.3%. In 2018, after a 2.0% COLA, that share fell to 28%, so with a 3.6% COLA the protection should matter for far fewer people.
The bigger picture on purchasing power
A 3.6% raise is welcome, but it’s worth keeping in perspective. AARP found that 80% of recipients said a 3.5% increase would not keep up with rising prices. The 2022 COLA was 5.9% while inflation ran around 9%, so that year left a real gap, even though 2023’s 8.7% made up some of it.
The practical takeaway is to treat the COLA as a reset rather than a windfall. When your new amount shows up in late November, compare it to what your regular bills have done this year. If the premium change or your own costs eat most of the increase, that’s useful to know before January, not after. And if you keep a small cushion in a savings account, the gap between when prices rise and when your benefit catches up becomes a lot easier to live with.
