Medicare 2026

Medicare for Active-Duty Families: When Part B Can Wait and When It Can't

Military families get a benefit most civilians don't: a built-in way to delay Medicare Part B without a lifetime late penalty while the sponsor is still serving. But the timing rules are strict, and missing the window can mean a gap in TRICARE and a permanent surcharge. Here's how it works in plain English.

How Medicare and TRICARE share the bill

The order of payment depends on whether the sponsor is still on active duty. According to Medicare.gov, if you're on active duty and have Medicare, TRICARE pays first for Medicare-covered services and Medicare pays second. If you aren't on active duty, Medicare pays first and TRICARE may pay second. TRICARE always pays for items and services you get from a military hospital or clinic.

That coordination is why Part B is optional during active-duty years for many family members — TRICARE is already the primary payer — but becomes essential later, when Medicare takes the lead.

The active-duty Special Enrollment Period

Active-duty service members and their family members who have Medicare based on age or disability (not ESRD) qualify for a Part B Special Enrollment Period with no late enrollment penalty. You can use this SEP:

• Any time the sponsor is on active duty and you're covered by TRICARE, or
• Within the first eight months after the month the sponsor's active duty ends or the month TRICARE coverage ends — whichever comes first.

This is a longer and more forgiving window than most workplace-coverage SEPs, but the eight-month clock is unforgiving once it starts.

A critical TRICARE note: enrolling in Part B after the sponsor retires causes a break in TRICARE coverage. TRICARE advises enrolling in Part B before the sponsor retires so coverage flows without a gap. And under the SEP, Medicare.gov says Part B starts the month after Social Security (or the Railroad Retirement Board) receives your completed forms — so timing your paperwork matters.

The paperwork you'll need

To use the active-duty SEP, Medicare requires an extra form that documents TRICARE coverage during the sponsor's active duty. TRICARE directs families to request a Verification of Military Health Care Benefits letter from the DMDC/DEERS Support Office. Gather this before you submit your Part B application so the SEP is honored and your effective date lines up with the loss of other coverage.

What happens if you miss the window

If the SEP lapses, the next opportunity is the General Enrollment Period, January 1 through March 31 each year. Part B and TRICARE coverage then begin the first day of the month after you sign up, and a Part B late enrollment penalty may apply. That penalty generally sticks for as long as you have Part B, so the SEP is worth protecting.

ESRD is treated differently

Family members who qualify for Part A because of end-stage renal disease cannot use the active-duty SEP. Because of that, TRICARE encourages ESRD-eligible family members to enroll in Part B as soon as they're first eligible, to avoid both a coverage gap and a penalty.

Why Part A at 65 is usually a no-brainer

Most people pay no premium for Part A because of their own or a spouse's work history. Medicare.gov notes that an active-duty spouse may want to sign up for Part A at 65 even while the service member is still serving. Regardless of age, active-duty family members with Part A may enroll in TRICARE Prime if they live in a Prime Service Area or, with a drive-time waiver, within 100 miles of an available primary care manager.

Part A alone doesn't disrupt TRICARE — it simply adds a second payer for hospital services.

What to think about for drug coverage

TRICARE includes prescription drug coverage that is generally considered creditable, meaning many military retirees do not need a stand-alone Part D plan. Still, it helps to understand how Part D works if you later decide you want it. For 2027, the Part D out-of-pocket cap is $2,400 (down from $2,100 in 2026), the maximum deductible any Part D plan may charge is $700, and the national base beneficiary premium — used to calculate any late-enrollment penalty — is $41.33. Individual plan premiums are set plan by plan.

Annual Enrollment for 2027 runs October 15 – December 7, 2026, with choices taking effect January 1, 2027.

Medicare Advantage vs. Original Medicare + Medigap

Once Part B is in the picture, retirees sometimes weigh Original Medicare (often with a Medigap policy) against a Medicare Advantage plan. Neither is universally better. Original Medicare offers broad provider access nationwide and predictable cost-sharing when paired with Medigap, but Medigap premiums are an added monthly expense. Medicare Advantage bundles coverage and often includes extras, but uses networks and prior authorization. TRICARE For Life coordination may also factor in for retirees. The right fit depends on your doctors, prescriptions, travel, and budget.

A note for people with Medicaid or Extra Help

Since 2025, people with Medicaid or Extra Help have a monthly Special Enrollment Period to move to Original Medicare with a stand-alone Part D plan, or to switch stand-alone Part D plans. Full-benefit dual-eligible individuals can join an integrated D-SNP in any month.

Other 2027 context

The Social Security Administration announced a 3.6% cost-of-living adjustment (COLA) for benefits payable beginning January 2027. CMS typically announces the 2027 Part B standard premium, Part B deductible, and IRMAA income brackets in the fall (usually November); those figures haven't been released yet.

Where can you get help with Medicare questions?

For personalized guidance, visit Medicare.gov or call 1-800-MEDICARE (1-800-633-4227), TTY 1-877-486-2048. For TRICARE-specific questions and the Verification of Military Health Care Benefits letter, contact the DMDC/DEERS Support Office.

This article is educational and is published by an independent, privately owned Medicare education site. It is not affiliated with the federal government or any government agency.