Last fact-check: July 27, 2026 · Primary source: Social Security Administration · Methodology explainer
Quick answer
SSA calculates the annual COLA from the percentage increase in the average CPI-W for July, August and September compared with the average for the third quarter of the last year a COLA became effective. The result is rounded to the nearest tenth of one percent. For 2026, 317.265 compared with 308.729 produced a 2.8% COLA.
Key takeaways
- The index is CPI-W, not CPI-U.
- SSA compares third-quarter averages, not one month to one month.
- If there is no increase—or rounding produces zero—there is no COLA.
The 2026 COLA calculation
| Step | Published value |
|---|---|
| Index | CPI-W |
| Base period | Q3 2024 average: 308.729 |
| Comparison period | Q3 2025 average: 317.265 |
| Raw calculation | (317.265 − 308.729) ÷ 308.729 |
| Rounding | Nearest tenth of one percent |
| 2026 result | 2.8% |
Why the third quarter is used
The Social Security Act formula uses the CPI-W average for the third quarter of the current measurement year and the third quarter of the last year when a COLA became effective. SSA does not choose the highest inflation month or use a calendar-year average.
When the result is announced
SSA determined the 2.8% COLA on October 24, 2025. It applies to Social Security benefits beginning with December 2025 benefits payable in January 2026 and to January 2026 federal SSI payment levels. SSA says the next COLA will be announced in October 2026.
COLA is not a forecast: before SSA publishes the required third-quarter data and official determination, any next-year percentage is only a projection.
What COLA does not measure
The formula does not measure one household’s personal cost increase, and it does not use the CPI-U headline series. COLA changes gross Social Security amounts; deductions such as Medicare premiums can change the net deposit separately.
Related guides
Official sources
Editorial status: This guide has been checked against the cited official sources. Independent subject-matter review has not been completed. Every index value and formula step was checked against SSA’s published computation on July 27, 2026. The Guru Gazette is independent and is not affiliated with SSA.