When the Social Security Administration announced in October that benefits would be rising by just 2.5% in the new year, many seniors were disappointed but not particularly shocked. For months, experts had been projecting that 2025's Social Security cost-of-living adjustment (COLA) would land somewhere in that ballpark.

Now, with the year winding down, all Social Security retirees should mark Nov. 20 as another date to remember. Here's why.