Cost-of-living adjustment

The adjustment is set by formula, not by decision. Under current law it is computed from the change in a specific price index — the CPI for Urban Wage Earners and Clerical Workers, CPI-W — measured over the third quarter against the same quarter of the last year in which an adjustment took effect.

Because it is formulaic and automatic, it is a good illustration of mandatory spending: no appropriation is passed, no vote is taken, and the outlay changes anyway. Congress wrote that autopilot. Leaving it in place is also a choice.

A COLA is not a rebate of inflation. It is a lagged, partial catch-up on one official basket, applied to the gross benefit. CPI-W is not every household’s basket; housing, insurance and out-of-pocket medical costs can move differently. The Medicare Part B premium is deducted from the same payment and moves separately, so the change in a person’s deposit can be smaller than the announced percentage — or, in a lean year, nearly nothing. See inflation.

A worked example

Take the CPI-W for July, August and September of the last year in which an adjustment took effect, and average them: say 300.0. Take the same three months this year: say 308.4. The ratio is 1.028, so the COLA is 2.8 percent, rounded to the nearest tenth. A $2,000 monthly benefit becomes $2,056 from the December payment, which arrives in January. If the second average had come in below the first, the COLA would be zero — not negative — and the following year’s comparison would still run against the earlier base.

That is the whole calculation. There is no discretion in it, and no one votes. The benefit is still $56 higher, and the price level that produced the 2.8 percent has already been paid.

How to read it in coverage

The figure is announced in October, when the September index is published, and applies to the following year. “Next year’s COLA will be X percent” is a projection until then; after the announcement it is a fact. The announced percentage applies to the gross benefit — the Medicare Part B premium deducted from the same payment moves separately. The site’s COLA page carries the current figure and a labelled projection of the next. A large COLA is not a windfall; it is evidence that prices already rose.