Most Medicare beneficiaries in New Mexico will pay $99.90 a month in premiums in 2012, a smaller-than-expected increase of $3.50, federal officials said Thursday.

About three-quarters of seniors and disabled people in New Mexico have been paying $96.40 a month for the Part B federal health-insurance program for the past three years. New enrollees—mainly people who turned 65 in 2009, 2010 or 2011—have been paying $115.40 a month. They will see their premiums decrease.

Medicare trustees predicted earlier this year they would boost premiums by up to $10 a month for most beneficiaries.

A law prevents most Medicare premiums from rising if Social Security payouts stay flat, which has been the case since 2009. The premiums paid by those not in a high-income category have been frozen for three years because of the law.

But the Social Security Administration said last week that recipients will see a 3.6% cost-of-living increase in their checks next year. That allowed Medicare’s costs to be spread across more recipients, not just those with higher incomes.

Individuals in the higher-income group—individuals who make over $85,000 a year, or couples earning over $170,000 a year—pay higher Medicare contributions, and paid larger premiums in each of the past three years to make up for the freeze for lower-income recipients. Their premiums will fall next year.