Medicare Supplement

Medigap Won't Cover Your Drugs — Here's How to Add Part D on Time

SOUTHFIELD, Mich. — If you're pairing Original Medicare with a Medigap policy, there's one gap the Medigap won't fill: your prescription drugs. That's a common surprise for new enrollees, and missing the timing on a stand-alone Part D plan can attach a penalty to your premium for as long as you have Medicare.

The good news is the three pieces — Original Medicare, Medigap, and Part D — are designed to fit together neatly once you know what each one does. Here's how they work as a set, and the dates that keep you out of the late enrollment penalty.

The three pieces, and what each one does

Think of Original Medicare, Medigap, and Part D as three separate tools that share the same job.

Original Medicare (Parts A and B) is the federal coverage itself. Part A helps pay for hospital stays; Part B helps pay for doctor visits, outpatient care, and durable medical equipment. It pays a large share of your covered medical costs, but it leaves deductibles and coinsurance for you.

Medigap (also called Medicare Supplement Insurance) is a private policy that helps pay some of what Original Medicare leaves behind — things like the Part A hospital deductible or the 20% Part B coinsurance, depending on which lettered plan you choose. It does not cover prescription drugs you pick up at a pharmacy.

Part D is a separate, stand-alone prescription drug plan sold by private insurers under Medicare rules. It's the piece that handles your pharmacy coverage when you have Original Medicare and Medigap.

Why Medigap doesn't include drugs

Older Medigap policies once bundled some drug coverage, but that changed when Congress created Part D. Since 2006, newly sold Medigap policies have not included prescription drug benefits. If you buy a Medigap policy today, you'll need a separate Part D plan (or other creditable drug coverage, like from an employer or the VA) to cover your medications.

That's different from a Medicare Advantage plan, which usually bundles drug coverage in. Original Medicare + Medigap keeps the pieces separate on purpose — which gives you flexibility, but also means you have to enroll in Part D yourself.

The timing that keeps you out of the late penalty

The Part D late enrollment penalty is a permanent add-on to your monthly premium. It kicks in if you go 63 days or more in a row without Medicare drug coverage or other "creditable" drug coverage after you're first eligible.

Here's how to stay clear of it:

• Enroll during your Initial Enrollment Period. For most people, that's a 7-month window around your 65th birthday — the three months before your birthday month, the month itself, and the three months after.
• If you delay because you have other drug coverage, make sure it's creditable (expected to pay, on average, as much as Medicare's standard drug benefit). Your employer, union, or retiree plan should send you a notice each year confirming this. Keep those notices.
• When that other coverage ends, you generally have 63 days to enroll in a Part D plan before the penalty clock starts.
• If you missed your window, you can still enroll during the Annual Enrollment Period, October 15 through December 7, for coverage starting January 1.

How the three fit together in Southfield

Southfield is in Oakland County, where a wide range of stand-alone Part D plans are offered to people with Original Medicare. Availability is set at the county level, so two neighbors on the same block generally see the same Part D options.

When you're comparing plans on Medicare.gov, you'll look at the monthly premium, the deductible (which cannot be more than $615 in 2026), the plan's formulary (its list of covered drugs), and the pharmacies in its network. Your Medigap policy is separate — it keeps doing its job on the medical side no matter which Part D plan you pick.

What's new for 2026 that helps drug budgeting

A couple of program changes have made Part D costs easier to predict:

• The coverage gap ("donut hole") is gone. As of 2025, Part D has three phases instead of four.
• A hard $2,100 out-of-pocket cap applies to covered drugs in 2026. Once you hit it, you pay $0 for covered prescriptions for the rest of the calendar year.
• The Medicare Prescription Payment Plan lets you spread your drug costs across the calendar year in monthly amounts instead of paying big bills at the pharmacy counter. It's optional, and you sign up through your Part D plan.

Higher-income enrollees should also know about IRMAA, an income-based surcharge on Part B and Part D premiums that begins above $109,000 in income for a single filer in 2026.