Medicare Planning · Price Services Group, L.L.C.

Medicare late enrollment penalties: 2026–2027 rules and costs

Missing a Medicare enrollment deadline can add an ongoing surcharge to your premiums. Special Enrollment Periods and other exceptions may prevent a penalty. Check the separate Part B and Part D rules before deciding to wait.

Kayla Price

Published June 13, 2026 · Updated October 25, 2026

Medicare penalties can have lasting costs. Part B and Part D penalties generally continue while you have the respective coverage, but exceptions and assistance programs matter. Verify your situation with Medicare or Social Security rather than assuming every missed deadline produces a lifetime penalty.

Enrollment rules and exceptions differ by Medicare part and by individual circumstances. This guide summarizes key timing and penalty rules; check with Medicare or Social Security before delaying enrollment.

The three penalties at a glance

Source: Medicare.gov — Avoid Late Enrollment Penalties.

Your Initial Enrollment Period (IEP)

People first eligible for Medicare at 65 generally have a 7-month Initial Enrollment Period centered on their 65th birthday month:

• 3 months before your birthday month
• Your birthday month
• 3 months after your birthday month

For Part B and premium-Part A, when you enroll matters for when coverage starts:

• Enroll in months 1–3 (before birthday month): coverage starts the 1st of your birthday month
• Enroll in month 4 (birthday month): coverage starts the 1st of the following month
• Enroll in months 5–7 (after birthday month): coverage starts the first of the next month

If you miss your IEP, check whether you qualify for a Special Enrollment Period. Otherwise, the General Enrollment Period for Part B and premium-Part A runs January 1 – March 31, with coverage starting the month after you sign up. A late enrollment penalty may apply. Premium-free Part A follows different rules.

The Part B penalty — how it adds up

The Part B late-enrollment penalty is generally 10% of the standard Part B premium for each full 12-month period you could have had Part B but did not, unless a Special Enrollment Period or other exception applies. Qualifying coverage is generally based on current employment; confirm your own eligibility and timing with Social Security.

Example: The 2026 standard Part B premium is $202.90/month. If you delayed Part B for 3 full years without qualifying coverage or another exception:

• 3 years × 10% = 30% penalty
• 30% × $202.90 = $60.87 before rounding
• After adding the penalty, the total monthly premium rounds to $263.80

The penalty generally continues while you have Part B. The dollar amount changes when the standard premium changes. The 2027 Part A and Part B premium and deductible amounts had not been announced as of October 25, 2026; check CMS for the official figures when released. Medicare Savings Programs and other exceptions may affect whether a penalty applies.

The Part D penalty — the drug coverage trap

You may owe a Part D penalty if, after your Initial Enrollment Period ends, you go 63 or more days in a row without Part D or other creditable prescription drug coverage. The calculation uses 1% of the national base beneficiary premium for each full uncovered month, rounded to the nearest 10 cents. The base beneficiary premium is $38.99 for 2026 and $41.33 for 2027. People receiving Extra Help do not pay this penalty.

Example using the 2026 base beneficiary premium of $38.99: 24 full uncovered months produce a 24% penalty. That is $9.3576, rounded to $9.40 per month, added to the plan premium. Using the 2027 base beneficiary premium of $41.33, the same 24-month calculation is $9.9192, rounded to $9.90 per month. Actual penalty assessments depend on your full coverage and enrollment history; the amount generally continues while you have Medicare drug coverage.

When comparing whether to enroll, review the plan premium, deductible, formulary, pharmacy network, and expected costs for your prescriptions. Drug coverage and costs vary by plan and year.

Delaying enrollment: check Part B and Part D separately

For Part B, group health coverage based on your or your spouse's current employment may qualify you for a Special Enrollment Period. Confirm which insurer pays first, especially with an employer of fewer than 20 employees. For Part D, obtain the plan's written creditable prescription drug coverage notice; employer health coverage alone does not establish drug creditability.

• Part B SEP: 8 months from when employment or employer coverage ends (whichever comes first)
• Part D SEP: generally two full months after the month employer or union coverage ends. Confirm your specific enrollment dates and avoid a 63-day drug coverage gap.

Critical distinction: the 8-month Part B SEP starts from when your active employment or employer coverage ends — not when COBRA ends. If you have employer coverage through March and COBRA runs through December, your 8-month clock starts in March, not December.

IRMAA — the income-related premium surcharge

Separate from late-enrollment penalties, higher-income Medicare beneficiaries pay an additional surcharge on Part B and Part D premiums called IRMAA (Income-Related Monthly Adjustment Amount). IRMAA is based on your Modified Adjusted Gross Income (MAGI) from 2 years prior.

If your income has dropped significantly since then (retirement, death of a spouse, loss of a business), you can appeal IRMAA using SSA Form SSA-44. Unlike late-enrollment penalties, IRMAA adjusts each year as your income changes.

How to avoid all of this

1. Know your 7-month IEP window and mark it on your calendar 6 months before you turn 65.
2. Verify current-employment group coverage and payment order with your benefits administrator. Separately request the written Part D creditable coverage notice.
3. Don't assume COBRA extends your Part B SEP. Its drug benefits may separately qualify as creditable for Part D.
4. If you lack creditable drug coverage, consider Part D even if you take no prescriptions. Compare costs and enroll during a valid window to avoid a future penalty.
5. Talk to a licensed Medicare agent before you turn 65, not after. The rules are straightforward once explained, but costly when misunderstood.

Reviewed October 25, 2026. Sources: Medicare.gov penalty rules and Part D calculation · Medicare.gov coverage start dates and SEPs · CMS 2026 premiums · CMS 2027 Part D base beneficiary premium. Price Services Group, L.L.C. is an independent licensed agency — we do not offer every plan available in your area.