Updated August 2, 2026. Quick answer: when a military retiree becomes eligible for Medicare, TRICARE does not simply continue. It becomes TRICARE For Life, which is wraparound coverage that sits behind Medicare — and it requires Medicare Part B. Decline Part B to avoid the premium and you do not keep TRICARE and save money. You lose TRICARE.
TRICARE’s own words
“If you’re eligible for both TRICARE and Medicare Part A, then in most cases, you must have Medicare Part B to keep TRICARE.”
TRICARE
And the consequence, stated just as plainly:
“You’ll lose your TRICARE coverage if you don’t have Part B, if you drop Part B, or you fail to pay your Part B premiums.”
TRICARE
Three ways to lose it, and the third is the cruel one: not a decision, just a missed payment.
Why the trap catches careful people
The reasoning that leads people wrong is entirely sensible. You have had TRICARE for decades. Part B costs a monthly premium. You are healthy, you already have coverage, so why pay twice?
Because TRICARE For Life is defined as “Medicare-wraparound coverage if you’re TRICARE-eligible and have Medicare Part A and Part B”. It is built to pay after Medicare. Without Part B there is no first payer for the services Part B covers, and the wraparound has nothing to wrap around. So the programme does not degrade gracefully — it stops.
The second reason it catches people: Part B has its own late-enrolment penalty that increases the premium permanently for each year you could have enrolled and did not. What that penalty comes to is worth running before assuming a deferral is free. Someone who declines at 65 and reconsiders at 70 pays more forever.
What to check, and when
Before your 65th birthday. Enrolment windows around 65 are unforgiving, and the general rules about employer coverage that let other people defer Part B do not rescue a retiree relying on TRICARE. If you are also still working and covered by an employer plan, that is a genuinely different analysis: the employer-coverage rules and how the count is done.
Keep paying it. If Part B premiums are not being deducted from a benefit payment, make sure they are being paid another way. The coverage you lose for a missed premium is not just Part B.
The cost side, honestly
Part B is a real monthly cost, and for higher-income retirees it is more than the standard premium because of the income-related surcharge, which is set from a tax return two years earlier — the lookback and why the tiers are cliffs. That is a genuine planning input, particularly if a large one-off year is coming.
What it is not is optional, if you intend to keep TRICARE.
Part B requirement, the TRICARE For Life definition and the loss-of-coverage consequence from TRICARE’s published pages. Read August 2026. Eligibility rules around Medicare enrolment are individual — confirm your own case with TRICARE and with Medicare. General information, not advice. Nothing here addresses how disability ratings are determined or pursued, which is outside what this site covers.