Original Medicare is two-fold, comprised of Part A (hospital insurance) and Part B (medical insurance). They differ not only in the Medicare benefits covered but also in how the premiums are determined.
Part A premium based on credits earned
Most people eligible for Part A have premium-free coverage. The premium is based on credits earned by working and paying taxes. When you work in the U.S., a portion of the taxes automatically deducted are earmarked for the Medicare program. Workers are able to earn up to four credits per year. Earning 40 credits qualifies Medicare recipients for Part A with a zero premium. A sliding scale is used to determine premiums for those who work less than 40 quarters. In 2020, this equates to $252 per month for 30 to 39 quarters and $458 per month for less than 30 quarters.
Part B premium based on annual income
The Part B premium, on the other hand, is based on income. In 2020, the monthly premium starts at $144.60, referred to as the standard premium. Once you exceed $87,000 yearly income if you file an individual tax return, or $174,000 if you file a joint tax return, the cost goes up to $202.40. As your income rises, so too does the premium amount until a certain level of income is exceeded based on tax return filing status. At that level, the monthly premium is set at $491.60. The amounts are reevaluated by Medicare annually and may change from year to year. Any amount charged above the standard premium is known as an income-related monthly adjustment amount (IRMAA).
How Medicare defines income
There is a two-year look-back period, meaning that the income range referenced is based on the IRS tax return filed two years ago. In other words, what you pay in 2020 is based on what your yearly income was in 2018. The income that Medicare uses to establish your premium is modified adjusted gross income (MAGI). Adjusted gross income is income less allowable adjustments as shown on Schedule 1 of Form 1040. MAGI adds back some of these adjustments. It is best to consult with an accountant on this calculation.
Additional payments for Medicare benefits
Another factor that affects the premium for Medicare benefits is the late enrollment penalty, which can be quite harsh. If you do owe a premium for Part A but delay purchasing the insurance beyond your eligibility date, Medicare can charge up to 10% more for every 12-month cycle you could have been enrolled in Part A had you signed up. This higher premium is imposed for twice the number of years that you failed to register. Part B late enrollment has an even greater impact. The 10% increase for every 12-month period is the same, but the duration in most cases is for as long as you are enrolled in Part B.