Last Updated: October 2026
If you have Tricare For Life (TFL), you may have received advertisements encouraging you to sign up for Medicare Part D. Maybe someone told you that you need it when you turn 65, or you've wondered whether adding it would help pay for your prescriptions. The good news? You don't have to enroll in Medicare Part D to keep your Tricare For Life coverage. Tricare already provides prescription drug coverage, and for many people, that's all they need. However, there are situations where adding Medicare Part D might be worth considering.
Let's look at how it works, what it could cost, and what you should know before making a decision.
First, What Is Medicare Part D?
Medicare Part D is prescription drug insurance offered by private insurance companies approved by Medicare. It helps pay for medications you pick up at a pharmacy or receive through a prescription delivery service. Some people purchase a separate Part D plan. Others have Part D included in their Medicare Advantage plan. Depending on the plan, you may pay a monthly premium, a deductible, and a portion of the cost of your prescriptions. Each plan also has its own list of covered medications and participating pharmacies.
One important distinction: Medicare Part B and Medicare Part D are not the same thing. Most people need Medicare Part B to maintain Tricare For Life eligibility. Medicare Part D is optional.
Doesn't Tricare For Life Already Cover Prescriptions?
Yes! When you have Tricare For Life, you also have access to the Tricare Pharmacy Program.
You can get covered prescriptions through:
Military pharmacies: Covered medications are available at no cost when the pharmacy carries them.
Tricare Pharmacy Home Delivery: You can receive up to a 90-day supply of many medications by mail.
Retail network pharmacies: These are participating pharmacies where you can fill covered prescriptions.
Non-network pharmacies: You can still fill prescriptions at some non-network pharmacies, but you may pay more and need to submit a claim for reimbursement.
Some medications require additional approval from Tricare before they're covered. If you'd like to learn more about how your existing pharmacy coverage works, visit our Complete Guide to the Tricare Pharmacy Program.
Will I Be Penalized If I Don't Sign Up for Part D?
This is one of the biggest concerns we hear from members. No, you won't face a Medicare Part D late enrollment penalty as long as you maintain your Tricare prescription coverage. Here's why. Medicare considers Tricare's pharmacy benefit creditable coverage. That's simply Medicare's way of saying your existing prescription coverage meets its standards.
Normally, someone who goes 63 consecutive days or longer without Medicare Part D or another qualifying prescription plan may face a penalty if they enroll in Part D later. Because your Tricare pharmacy coverage qualifies, you can choose not to enroll in Part D without worrying about that penalty while your Tricare coverage remains active. However, this doesn't mean you can sign up for Part D whenever you want. You still need to enroll during an eligible enrollment period.
So Why Would Someone with Tricare For Life Want Part D?
For many people, adding Part D would mean paying for another prescription plan they may not need. But there are a few situations where it might make sense.
1. A Medication Isn't Covered by Tricare
Not every prescription medication is covered by Tricare. If you're taking something Tricare won't cover, it's possible that a Medicare Part D plan might cover it. For example, let's say Tricare denies coverage for a medication your doctor prescribed. You find a Part D plan that includes that medication.
Before enrolling, you'd want to find out:
Does the Part D plan cover your exact medication and dosage?
Does it require approval before paying?
How much would you pay each month for the plan?
How much would the medication cost you?
Would the savings be worth paying for another insurance plan?
Keep in mind that just because a medication appears on a plan's covered drug list doesn't mean it will automatically be approved.
2. You Qualify for Medicare's Extra Help Program
Medicare has a program called Extra Help that assists people with limited income and resources in paying for prescription drug coverage. If you qualify, Extra Help may reduce what you pay for a Part D plan and your medications. For some members, this could make Part D worth considering.
You can learn more at https://www.medicare.gov/basics/costs/help/drug-costs.
3. You're Interested in Certain Weight-Loss Medications
This is a newer consideration for Tricare For Life members. Beginning August 31, 2025, Tricare stopped covering GLP-1 medications prescribed solely for chronic weight management for Tricare For Life members. This restriction also applies at military pharmacies.
However, Medicare introduced a temporary program called the Medicare GLP-1 Bridge Program beginning July 1, 2026. Through this program, eligible people enrolled in Medicare Part D may be able to receive certain weight-loss medications, including Wegovy, Zepbound, and Foundayo. Those who qualify pay $50 for a monthly supply through the program. There are specific medical requirements, and your doctor may need to submit information showing that you qualify. Simply having Part D doesn't guarantee that you'll be approved. The $50 payment also doesn't count toward your Part D deductible or annual out-of-pocket limit.
If you're thinking about enrolling in Part D just for a weight-loss medication, check whether you qualify for the program first.
You can review Medicare's official information here: https://www.medicare.gov/coverage/weight-loss-drugs
What Happens If I Have Both Part D and Tricare?
You can have both. When a prescription is covered by both plans, Medicare Part D pays first. Tricare may then help pay eligible remaining costs, depending on its coverage rules. This doesn't mean every prescription will be free. For example, if your Part D plan pays part of the cost of a medication, Tricare may cover some or all of the remaining eligible amount. However, if the medication isn't covered under Tricare's rules, you could still owe money. You'll want to make sure your pharmacy has both insurance plans on file. When possible, use a pharmacy that participates in both your Part D plan and Tricare's retail pharmacy network. This can help avoid billing problems.
Important: Part D Can Affect Tricare Pharmacy Home Delivery
This is something I especially want members to understand before enrolling. If you have Medicare Part D prescription coverage, you ordinarily cannot use Tricare Pharmacy Home Delivery. There are exceptions, such as when your other prescription plan doesn't cover a medication or you've used up its prescription benefit limit. You may need to provide documentation.
Why does this matter? Let's say you've been receiving your regular prescriptions through Express Scripts Home Delivery for years. You decide to purchase Medicare Part D because you think it might save money on one medication. That decision could affect how you receive your other prescriptions. You may need to switch those medications to a retail pharmacy instead. That doesn't mean Part D is a bad choice. It just means you should understand what you're gaining and what might change before enrolling.
Will Part D Cost Me More Money?
It could. Medicare Part D plans can have monthly premiums, deductibles, copayments, and other costs. Some people also pay an additional amount based on their income, called IRMAA. Even if a plan advertises a $0 monthly premium, that doesn't necessarily mean your prescriptions will be free. Before purchasing a plan, compare what you currently pay through Tricare with what you would pay if you added Part D. For some people, adding Part D could save money. For others, it could mean an extra monthly expense without much benefit.
What If I Already Have Medicare Advantage?
Some Medicare Advantage plans include Medicare Part D prescription coverage. If your Medicare Advantage plan includes prescription benefits, you may already have Part D without realizing it. Before signing up for another prescription plan, check what your Medicare Advantage plan already includes. Enrolling in a separate Part D plan can also affect your Medicare Advantage enrollment, so it's important to understand how your plan works before making changes.
You can learn more in our Medicare Advantage vs. Original Medicare guide.
When Can I Sign Up for Medicare Part D?
You can enroll when you first become eligible for Medicare. You can also enroll or change plans during Medicare's annual Open Enrollment Period, which runs from October 15 through December 7. Changes made during this period take effect January 1. Certain life events may also qualify you for a Special Enrollment Period.
Because Tricare provides creditable prescription coverage, you don't need to enroll in Part D just to avoid a penalty. However, you still have to follow Medicare's enrollment rules if you decide to sign up later.
For members living overseas: Medicare Part D is not available to people residing outside the United States and its territories. Tricare's overseas pharmacy benefits remain available for covered prescriptions.
Common Questions
If I don't sign up for Medicare Part D at 65, will I lose Tricare For Life?
No. Medicare Part D is not required to keep Tricare For Life. Most members need Medicare Part A and Part B, not Part D.
Will Tricare automatically sign me up for Medicare Part D?
No. Tricare's prescription drug coverage is separate from Medicare Part D.
Can I still use military pharmacies if I have Part D?
Yes. You can continue getting covered medications at no cost when they're available through a military pharmacy.
However, military pharmacies are required to bill other prescription insurance, including Medicare Part D, when applicable. Make sure they have your current insurance information.
If Tricare won't cover my medication, will Medicare Part D cover it?
Not necessarily. Every Part D plan has its own medication coverage rules. You'll need to check whether a particular plan covers your prescription.
Can I cancel Medicare Part D if I decide I don't need it?
Yes, but you must follow Medicare's enrollment and disenrollment rules. If you have Medicare Advantage, dropping Part D could also affect your medical coverage, depending on your plan.
The Bottom Line
If you have Tricare For Life, you already have prescription drug coverage. You don't need Medicare Part D simply because you're turning 65, and you won't face a Part D late enrollment penalty while you maintain your Tricare pharmacy coverage.
However, Part D may be helpful in certain situations, especially if you're taking a medication Tricare doesn't cover or you qualify for additional assistance through Medicare. Before enrolling, take a look at the medications you use, what you're currently paying, and whether adding Part D would actually save you money. And don't forget to consider how it could affect Tricare Pharmacy Home Delivery.
The goal isn't to have more insurance. It's to make sure the coverage you have works for you.
Educational Disclaimer
The Tricare For Life Care Initiative (TFLCI) is an independent 501(c)(3) nonprofit organization dedicated to providing educational information to military retirees and their families. We are not affiliated with or endorsed by the Department of Defense, Defense Health Agency, Tricare, Medicare, or the Social Security Administration.
This article is for educational purposes and is not individualized insurance advice. Coverage, eligibility, costs, and enrollment rules can change. Always verify your specific situation with the appropriate agency or plan before making coverage decisions.