How the 2027 adjustment was calculated
Social Security has confirmed that monthly benefits will increase by 3.6% starting in January, 0.8 percentage points more than the adjustment recipients received this year. The figure is the fifth-largest in the past 35 years, a reflection of price pressures that have persisted through much of 2026. The agency does not use the headline inflation number most Americans see; it relies instead on the CPI-W, an index built around the spending patterns of hourly wage earners and clerical workers, a group covering roughly 30% of the U.S. population.[S1]
In September, the CPI-W climbed 3.9% compared with a year earlier, the second-biggest annual increase of 2026 after May's 4.4% jump. The broader CPI-U, the country's main inflation gauge, stood at 3.7% for the same month. The gap between the two measures stems from the different weights each assigns to categories such as rent, transportation, food and beverages, apparel, and fuels and utilities. Since April, the CPI-W has exceeded the CPI-U every month; the two were level in March.[S1][S2]
The benefit increase is derived from the third-quarter average of the CPI-W, which is compared with the prior year's average and rounded to the nearest tenth of a percent. This year's third-quarter average came in 3.62% above the 2025 figure, producing the 3.6% adjustment. July and August matter to the calculation because, together with September, they form that quarter; CPI-W inflation measured 3.4% and 3.5% in those two months before accelerating in September.[S1]
Energy prices behind the acceleration
Much of the September pickup traces to energy costs, which rose sharply as the conflict in the Middle East disrupted supply. The closure of the Strait of Hormuz, a waterway that carries an estimated 20% to 25% of the world's oil, sent prices higher. Overall energy costs were up 20.4% year over year in September, gasoline of all types jumped 34.2%, and fuel oil surged 74.2%. Energy services rose 4.6%, electricity 4.4%, and utility gas service 5%.[S1]
For households that have recently paid at the pump or opened a utility bill, those figures will not come as a surprise. Inflation had briefly moderated in July and August before geopolitical tensions renewed the upward pressure in September. The new adjustment will not fully offset the price increases recipients are currently absorbing, and it will not arrive until January. Even so, with the official number now published, beneficiaries can begin revising their 2027 budgets around a known income figure rather than an estimate.[S1]
