Social Security recipients won't be getting big benefit increases next year, but the small raises they will get are playing an important role in helping seniors grow their incomes. This comes as younger workers lose ground.

Preliminary figures show the annual benefit boost will be between 1 and 2 percent, which would be among the lowest since automatic adjustments were adopted in 1975. Monthly benefits for retired workers average $1,237, meaning the typical retiree can expect an extra $12 to $24 a month.

The size of the cost-of-living adjustment, or COLA, will be made official Tuesday, when the government releases inflation figures for September. “The COLA continues to be very critical to people in keeping them from falling behind,” said David Certner, AARP’s legislative policy director.

How important is the COLA? From 2001 to 2011, household incomes in the U.S. dropped for every age group except one: those 65 and older.

The median income for all U.S. households fell by 6.6 percent, when inflation was taken into account, according to census data. But the median income for households headed by someone 65 or older rose by 13 percent.

Seniors still, on average, have lower incomes than younger adults. Most older Americans rely on Social Security for a majority of their income, according to the Social Security Administration.

This year, Social Security recipients received a 3.6 percent increase in benefits after getting no increase the previous two years. Many seniors feel like the COLA doesn’t cover their rising costs.