Medicare 2026

Part B and Part D penalty rules for Arlington Medicare enrollees

ARLINGTON, Va. — For Medicare, the calendar is everything. Miss the wrong window by even a month, and you can end up paying a penalty tacked onto your premium for as long as you have coverage. The good news: the deadlines are fixed, published, and easy to plan around once you know how they line up.

This guide walks Arlington readers through the enrollment windows that trigger Part B and Part D late penalties, what happens if one slips by, and how the dates fit together.

The seven-month window that starts everything

Most people become eligible for Medicare at 65. Your Initial Enrollment Period (IEP) is a seven-month window: the three months before your 65th birthday, the month you turn 65, and the three months after. Sign up during that window and no penalty applies.

Signing up in the three months before your birthday month means coverage starts the first day of your birthday month. Signing up after your birthday month delays your start date, so most people who don't have other coverage aim for the earlier half of the window.

If you miss the IEP and don't qualify for a special exception, you generally have to wait for the General Enrollment Period, January 1 through March 31, with coverage starting the month after you enroll. That gap between eligibility and enrollment is where the Part B penalty is calculated.

How the Part B penalty is built — and why it usually never goes away

The Part B late enrollment penalty is 10% of the standard Part B premium for each full 12-month period you could have had Part B but didn't. It's added to your monthly premium and, in almost all cases, you pay it for as long as you're enrolled in Part B.

Two full years late means 20% added on top of the premium. Four years late means 40%. Because the penalty is a percentage of the current-year premium, it also grows a bit each year as the base premium changes.

The Part D penalty is smaller per month — but it stacks

Part D works differently. The penalty is 1% of the "national base beneficiary premium" for each full month you went without creditable prescription drug coverage after your Initial Enrollment Period ended. "Creditable" means coverage the government considers at least as good as a standard Part D plan — often employer or union drug coverage.

Because the penalty is counted in months, not years, even shorter gaps add up. Twenty months without creditable coverage becomes a 20% add-on to the base premium, and it sticks to your Part D premium for as long as you have Part D.

The takeaway for timing: if you don't take a drug plan at 65 because you're not on medications, you still need creditable drug coverage from somewhere — or you'll owe the penalty later when you finally enroll.

When the dates interact: three common Arlington scenarios

Turning 65 with no other coverage. Enroll during your seven-month IEP for both Part B and Part D. Waiting for the General Enrollment Period (Jan. 1 – March 31) means a late-enrollment penalty and a delayed start.

Still working at 65 with employer coverage. If your employer plan is creditable, you can usually delay Part B and Part D without penalty. When the job or coverage ends, an eight-month Special Enrollment Period opens for Part B, and a 63-day window for Part D. Miss those, and the penalty clocks start counting from when your IEP ended — not from when your job coverage stopped.

Enrolled in Part A only. Many people take premium-free Part A at 65 and postpone Part B. That's fine if you have other creditable coverage. Without it, the Part B penalty accrues quietly in the background.

Arlington is in Arlington County, where residents can compare Medicare Advantage and Part D plan options during the Annual Enrollment Period, Oct. 15 – Dec. 7, and the Medicare Advantage Open Enrollment Period, Jan. 1 – March 31. Those windows are for changing plans, not for first-time Part B enrollment.

How to keep the penalty clocks at zero

• Mark your seven-month IEP on the calendar as soon as you know your Medicare start date.
• If you're staying on a workplace plan past 65, get written confirmation from HR that the drug coverage is creditable, and keep the notice.
• When you retire or lose group coverage, act inside the Special Enrollment Period — don't wait for the next general window.
• If you take even one prescription, pair Part B enrollment with a Part D decision so a gap doesn't open.

Where to get personalized help

Penalty math depends on your exact dates, and one document — like a creditable-coverage letter from an employer — can change the outcome. For personalized answers, contact:

• Medicare: medicare.gov or 1-800-MEDICARE (1-800-633-4227), TTY 1-877-486-2048.
• Virginia SHIP (Virginia Insurance Counseling and Assistance Program): free, unbiased counseling for Arlington residents.
• Social Security: ssa.gov or 1-800-772-1213, since Social Security handles Part B enrollment.