The Centers for Medicare & Medicaid Services says that while the standard monthly Part B premium will rise to $115.40 in 2011, most Medicare beneficiaries will not see an increase in their monthly Part B premiums.

This is because of a hold-harmless provision in current law that will freeze Part B premiums at the amount paid in 2010.

It is those who newly enrolled in Medicare Part B during 2010 who will pay the new $115.40 monthly premium in 2011.

Additionally, those who do not have their Part B premiums withheld from Railroad Retirement or Social Security payments, or those subject to income-related additional premium amounts will pay a higher premium in 2011.

The income-related additional premium threshold is annual adjusted income of $85,000 for individuals and $170,000 for married couples.

The Centers for Medicare & Medicaid Services estimates that only about 5 percent of Medicare beneficiaries with Part B will pay higher premiums in 2011 because of their higher annual incomes.

As for Medicare Part D prescription drug coverage plans, those premiums vary from plan to plan.

Beginning in 2011, the Affordable Care Act requires Medicare Part D participants, whose modified adjusted gross incomes exceed the $85,000 and $170,000 thresholds, to pay a second premium in addition to the standard Plan D premium.

Medicare beneficiaries affected by the 2011 Part B and D income-related premiums will receive a notice from the Social Security Administration with further details on the higher Part B and Part D premiums they will face.