Late enrollment penalty calculator

How does the Part B penalty work?

When you first become eligible, you have a seven-month Initial Enrollment Period around your 65th birthday month. If you don't sign up for Part B then, and you don't have group health coverage from your own or your spouse's current job, Medicare counts the months until you do sign up. Each full 12 months adds 10% of the standard premium. A 30-month gap is two full periods, so 20%. In 2026 that is 20% of $202.90, about $40.58 a month on top of your premium.

The penalty follows the standard premium, so it rises when the premium does, and you generally pay it for as long as you have Part B. Coverage that doesn't protect you from the Part B penalty includes retiree coverage, COBRA, Marketplace plans, VA health care, and care through the Indian Health Service or a tribal health program. That matters for Oklahoma public retirees: a HealthChoice Medicare supplement plan from EGID is retiree coverage, and EGID says those plans pay as if you have Part B, so going without Part B can leave you with both a gap and a penalty. See state and teacher retirees and Medicare, working past 65 and, for TRICARE users, veterans, TRICARE and military retirees.

How does the Part D penalty work?

The Part D penalty applies if, after your Initial Enrollment Period, you go 63 days or more in a row without a Medicare drug plan or other creditable drug coverage. Creditable coverage is drug coverage expected to pay at least as much as standard Part D; your employer, union or other plan sends a notice each year saying whether yours is. Keep those notices: they are your proof if Medicare later asks.

The penalty is 1% of the national base beneficiary premium for each full month without coverage. In 2026 the base premium is $38.99, so a 24-month gap adds 24% of it to your monthly drug plan premium: $9.36 before Medicare rounds it to the nearest 10 cents. The base premium changes every year, so the penalty does too. More on drug plans is on Medicare Part D in Oklahoma.

How can Oklahomans get the penalties removed?

Medicare says that if you enroll in a Medicare Savings Program you won't pay a Part B late penalty, and if you qualify for Extra Help you don't pay a Part D late penalty.

• SoonerCare Medicare Savings Programs. SoonerCare pays your Part B premium, and with QMB also your Medicare deductibles and coinsurance. Oklahoma Human Services checks income and resources; in 2026 countable resources must be no more than $9,950 for one person or $14,910 for a couple, and your home and car don't count. Apply online through OKDHSLive or at an OKDHS Human Services Center, and check your numbers with the savings programs screener. Read Medicare Savings Programs in Oklahoma.
• Extra Help. If you are in a Medicare Savings Program, have full SoonerCare or get Supplemental Security Income, you get Extra Help automatically. Otherwise you can apply with Social Security. Its resource limit is higher than the savings programs' limit.
• Special Enrollment Periods. If you had job-based coverage from current work, including a job with a tribal nation, a school district or the state, you generally have eight months after that job or coverage ends to sign up for Part B without a penalty. See enrollment periods for this and other situations.

Sources

• Medicare.gov — Avoid late enrollment penalties
• Medicare.gov — Part D costs and the late enrollment penalty
• Medicare.gov — Creditable prescription drug coverage
• CMS — 2026 Medicare Parts A & B premiums and deductibles
• Indian Health Service — Dear Tribal Leader and Urban Indian Organization Leader letter on the Medicare Part D creditable coverage letter, October 15, 2026 (PDF)
• Oklahoma Human Services — Appendix C-1, Maximum Income, Resource, and Payment Standards
• Oklahoma Human Services — Program FAQs (OKDHSLive)
• Oklahoma Health Care Authority — SoonerCare Supplemental
• EGID — 2027 HealthChoice Medicare supplement application (Part B note) (PDF)

Frequently asked questions