Enrollment
Medicare late enrollment penalties: Part A, B and D
Medicare isn't mandatory, but signing up late can cost your parent for years. The penalty is a permanent add-on to the premium, not a one-time fee. The good news: in many situations it doesn't apply at all. Here is how Medicare calculates it, and when it doesn't apply.
Part B: 10% for each full year
Someone who could have signed up for Part B and didn't pays an extra 10% of the standard premium for each full 12 months they waited. For most people the penalty lasts as long as they have Part B, usually for life.
The medicare.gov example: a 24-month delay means a 20% penalty. With the 2026 standard premium of $202.90, that person pays $243.50 a month. In 2027 the premium is projected at about $209.50 per the Medicare Trustees Report projection, so with that penalty about $251.40 a month. CMS announces the final 2027 premium in the fall.
Anyone who missed their first window can sign up in the General Enrollment Period, January 1 to March 31. Coverage starts the month after sign-up. The penalty stays.
When there's no Part B penalty
The most common exception is job-based coverage. If your parent or their spouse is still working and has group health coverage from that job, Part B can wait. When the job or that coverage ends, a Special Enrollment Period lasts 8 months, from whichever happens first, with no penalty.
Coverage that isn't based on current employment, such as COBRA or retiree coverage, works differently. Check before dropping or delaying Part B.
Part D: 1% for each month without drug coverage
The Part D penalty applies to people who didn't join a drug plan when first eligible, or who went 63 days or more in a row without Medicare drug coverage or other creditable drug coverage.
Medicare multiplies 1% by the number of full uncovered months, and that by the national base beneficiary premium: $38.99 in 2026 and $41.33 in 2027 (CMS, July 28, 2026). The amount is rounded to the nearest 10 cents and added to the plan premium. The medicare.gov example: 14 months is 14%, or $5.50 a month in 2026. In 2027 the same penalty is $5.80 a month. It lasts as long as your parent has Medicare drug coverage, even after switching plans.
People who get Extra Help don't pay the Part D penalty.
Part A: only if it has to be bought
Most people get Part A with no premium, so there's no penalty. Someone who has to buy Part A and signs up late pays a 10% higher premium for twice the number of years they waited. Two years late means four years of the higher premium.
Sources: medicare.gov (avoiding late enrollment penalties; Part D costs), the CMS 2026 premium announcement, the CMS fact sheet of July 28, 2026 for the 2027 base premium, and the 2026 Medicare Trustees Report for the projected 2027 Part B premium. If you're not sure whether your parent's job coverage protects them, we can check it together, in Polish for them and in English for you, with no obligation to enroll. Book a consultation.