The Social Security Administration (SSA) has released its 2018 Medicare Premiums: Rules for Higher-Income Beneficiaries annual report which provides guidelines for income-adjusted Medicare drug premiums. Higher-income beneficiaries are required to pay an income-adjusted premium amount for their Part B and prescription drug coverage. This adjustment is calculated based on your modified adjusted gross income (MAGI) and filing status from your most recent Federal tax return. While these premiums only affect roughly 5 percent of people with Medicare, it is important to know the income thresholds as they will directly impact the monthly amount you will be required to pay.
The SSA guide provides a number of different resources in order to determine whether you will be required to pay an income-related premium, all of which can be found here. In addition to the income tables, you will also find advice and helpful instructions on how to appeal a potential premium in the event you feel this was calculated in error.
Source: Medicare.gov, http://www.medicare.gov/your-medicare-costs/costs-at-a-glance/costs-at-glance.html