Social Security COLA 2027 forecast: September’s gas spike tilts it toward 3.6%

The 2027 Social Security cost-of-living adjustment is two-thirds decided, and the last third is being set at the gas pump. Official consumer price data for July and August put the raise at 3.3% so far. September’s reading, due Oct. 14, will round it up to 3.5% if the price index Social Security uses rises at least 0.17% from August, and to 3.6% if it rises at least 0.46%. Gasoline has already done a large share of that work: regular gas averaged $4.319 a gallon nationally on Monday, and September’s first two weekly readings ran 4.4% above the August average, according to the Energy Information Administration.

Run those pump prices through the formula and the 2027 COLA tilts toward 3.6%, a tenth of a point above the 3.5% that The Senior Citizens League forecast on Sept. 11, before the latest jump in gas prices. TECHi’s calculation, laid out below, lands on 3.6% in seven of eight scenarios and on 3.5% in the eighth. For the average retiree the gap is $1.94 a month. For a week in which the Federal Reserve is expected to raise rates, it is one more inflation number moving the wrong way.

5 Points30s Read

1. 01Locked in–July and August CPI-W data put the 2027 Social Security COLA at 3.3% so far, measured against SSA’s third-quarter 2025 base of 317.265.
2. 02The September math–The CPI-W must rise at least 0.17% from August to September for a 3.5% COLA and at least 0.46% for 3.6%; a normal September of the last four years would deliver 3.5%.
3. 03The gas spike–Regular gasoline hit $4.319 a gallon on Sept. 14, and September’s first two weekly readings averaged 4.4% above August, per EIA. Gasoline is about 5.3% of the CPI-W, so that alone adds roughly 0.23 to 0.28 points.
4. 04TECHi’s estimate–Combining those gas prices with the last four Septembers gives a COLA of 3.6% in seven of eight scenarios and 3.5% in one, with several results just above the 3.55% rounding line.
5. 05The dollars–On a $1,940.08 average check, 3.5% adds $67.90 a month and 3.6% adds $69.84; the projected Part B premium rise of $6.60 takes back part of either. SSA announces the COLA on Oct. 14.

Social Security COLA 2027 forecast: 3.3% is locked in, September decides the rest

The formula leaves little room for interpretation. A COLA “is equal to the percentage increase (if any) in the CPI-W from the average for the third quarter of the current year to the average for the third quarter of the last year in which a COLA became effective,” and “if there is an increase, it must be rounded to the nearest tenth of one percent,” the Social Security Administration explains. The CPI-W is the Consumer Price Index for Urban Wage Earners and Clerical Workers. The base for 2027 is the third-quarter 2025 average, which SSA computed at 317.265 when it set the 2.8% raise paid this year.

Two of the three months are now published. The CPI-W stood at 327.104 in July and 328.481 in August, up 3.4% and 3.5% from a year earlier, according to Bureau of Labor Statistics data. The average of those two months is 3.32% above the base, which is where the “3.3% so far” comes from. September’s index then moves the quarterly average, and TECHi worked back from SSA’s rounding rule to find the change from August that each outcome needs:

• 3.4% COLA: September CPI-W no more than 0.12% below August.
• 3.5% COLA: September CPI-W at least 0.17% above August.
• 3.6% COLA: at least 0.46% above August.
• 3.7% COLA: at least 0.75% above August.

For scale, the CPI-W rose 0.08% from August to September in 2022, 0.23% in 2023, 0.13% in 2024 and 0.26% in 2025, on the same unadjusted basis SSA uses. A normal September would deliver 3.5%. It takes an unusual one to reach 3.6%, and gasoline is making this one unusual.

The Senior Citizens League cut its forecast to 3.5% from 3.6% after the August data, and said its final estimate would stand until the announcement. “The biggest thing we’re watching with the COLA announcement coming are short-term shocks to the economy that push inflation way up or down in the next 30 days,” executive director Shannon Benton said in the group’s forecast. A 4.4% jump in gasoline in the first half of September is that kind of shock.

Why gas prices decide the 2027 COLA

The CPI-W is built around the spending of working households, and those households spend more of their budget on fuel. Gasoline carried a relative importance of 3.971% in the CPI-W in December 2025, against 2.895% in the broader CPI-U, according to the BLS relative importance table. Weights drift with prices between updates, and gasoline prices have not stood still. The CPI-W gasoline index rose 38% from December to August, and was up 27.7% from a year earlier in August, per BLS data, which puts gasoline’s effective share of the index at about 5.3% by August, by TECHi’s arithmetic.

The pump-price data arrives weekly, a month ahead of the CPI. Regular gasoline averaged $4.058 a gallon across August’s five weekly readings, then rose to $4.157 on Sept. 7 and $4.319 on Sept. 14, according to EIA’s weekly retail price series. A year earlier, on Sept. 15, 2025, the same gallon cost $3.168. The run-up began in March, when the national average climbed from $3.015 to $3.990 in four weeks, and it has tracked the oil market since; Brent crude was trading near $106 a barrel on Tuesday, and TECHi’s oil price page and gas price page follow both.

EIA prices are not the CPI, so TECHi tested how closely one predicts the other. Across 44 months since early 2023, the monthly change in EIA’s average regular gas price and the monthly change in the CPI-W gasoline index moved almost in lockstep, with a correlation of 0.997, an average gap near zero and a typical miss of about 0.4 percentage points. In August, EIA’s average rose 3.2% and the CPI-W gasoline index rose 2.7%. On that relationship, September’s first two weeks imply a gasoline index gain of about 4.3%; if prices hold at Monday’s $4.319 for the rest of the month, about 5.3%.

At a 5.3% weight, gasoline alone would add roughly 0.23 to 0.28 percentage points to the September CPI-W. That clears the 0.17% needed for 3.5% before anything else in the index moves. It is also the opposite of a typical September: the CPI-W gasoline index fell 5.4% in September 2022 and 5.0% in September 2024, as summer driving demand faded.

TECHi’s estimate: 3.6% in seven of eight scenarios

Everything other than energy tends to rise in September. The CPI-W excluding energy increased 0.40% from August to September in 2022, 0.21% in 2023, 0.38% in 2024 and 0.27% in 2025, per BLS data, and it rose 0.31% in August 2026. TECHi combined each of those four September patterns with the two gasoline paths above, giving eight scenarios for the September CPI-W:

• Gasoline at September’s first-two-week average: September CPI-W up 0.43% to 0.61%, a COLA of 3.5% in the 2023-like case and 3.6% in the other three.
• Gasoline holding at $4.319: September CPI-W up 0.48% to 0.66%, a COLA of 3.6% in all four cases.
• No scenario reaches 3.7%, which would need a 0.75% rise.

The margin is thin, and it should be read that way. Three of the 3.6% outcomes compute to between 3.556% and 3.576%, just above the 3.55% line where SSA’s rounding flips from 3.5% to 3.6%. The model does not separately price electricity and natural gas, which sit inside the CPI-W’s 8.1% energy weight, and a 0.4-point miss on gasoline moves the headline by about 0.02 points. What it does show is how far pump prices would have to fall to put 3.4% back in play: a September average about 8% below August, which after two weeks above $4.15 would mean regular gas near $3.24 for the rest of the month.

How much Social Security checks would rise in 2027

The average Social Security check is $1,940.08 a month, according to The Senior Citizens League. A 3.5% COLA would raise it by $67.90, to $2,007.98. A 3.6% COLA would raise it by $69.84, to $2,009.92. The difference is $1.94 a month, or $23.28 over 2027. A 3.4% COLA, the outcome that now looks out of reach, would add $65.96.

Part of the raise is spoken for. The standard Medicare Part B premium, which most beneficiaries have deducted from their checks, is projected to rise to $209.50 a month in 2027 from $202.90, an increase of $6.60, according to the Medicare trustees’ projections reported by MOAA. The Centers for Medicare & Medicaid Services usually sets the final figure in the fall. At a 3.6% COLA and that premium, the average net increase would be about $63.24 a month.

Timing follows the usual pattern. This year’s 2.8% increase applied to December 2025 benefits payable in January 2026, and SSI payments for January are made at the end of December, per SSA, so a 2027 raise would first show up in checks paid in January 2027. At 3.5% or 3.6%, it would be the largest COLA since the 8.7% paid in 2023, following 3.2% in 2024, 2.5% in 2025 and 2.8% in 2026.

What the COLA says about inflation and the Fed

A larger COLA is not good news in itself. It is a receipt for prices already paid, and the source of this one is energy rather than the broad economy. Consumer prices for all urban consumers rose 3.4% in the year to August while the index excluding food and energy rose about 2.5%, per BLS data, a gap that is almost entirely fuel. That is the same shock that pushed the 10-year Treasury yield above 5% on Tuesday for the first time since 2007, as TECHi reported that morning, and that has traders pricing a 92% chance of a quarter-point Fed rate increase on Wednesday, Reuters reported.

For retirees, that combination cuts both ways. A higher COLA offsets gasoline and grocery bills with a lag of up to a year, and higher interest rates lift the yields on savings accounts, certificates of deposit and Treasury bills. It also means the costs that a COLA is meant to cover are still rising in September, while the 2027 raise will be fixed on the third-quarter average and paid through next December.

When the 2027 COLA will be announced

The Bureau of Labor Statistics publishes September consumer prices on Oct. 14, and SSA announces the COLA the same day, according to The Senior Citizens League. Two more weekly EIA gasoline readings, on Sept. 21 and Sept. 28, will show whether pump prices hold above $4.30 through the end of the quarter. If they do, a 3.6% COLA becomes the more likely outcome. If gasoline falls back toward August’s $4.06 average, the raise settles at 3.5%, where most forecasts have it now.