New Mexico Medicare · Prescriptions & plan changes

Keep Your Medications When Your Plan Changes: 2027 Guide for New Mexico

In 2027, Presbyterian's Medicare Advantage exit and Humana's reductions will force about 30,000 New Mexico seniors to switch plans during October–December enrollment. This guide covers the step-by-step way to maintain your current medications, handle prior authorization, avoid pharmacy gaps, and use the plan's transition fill when coverage begins January 1.

By the New Mexico Medicare Help Data Desk

Reviewed by Brian Penner, Independent Medicare advisor — no pressure · Updated August 7, 2026

When your Medicare plan changes — whether you're switching because your old plan is ending, or you chose a new one during enrollment — your medications don't automatically follow. Each plan has its own formulary (drug list), copay structure, and prior authorization rules. The good news: Medicare has built-in safety nets to keep you from running out of medication. The catch: they only work if you act during the enrollment window (Oct 15 – Dec 7, 2026). On January 1, 2027, when your new plan starts, you'll get a one-time transition fill if your new plan doesn't cover a drug your old plan did — but that's just a 30-day bridge. The real work happens before then, when you check the new plan's formulary and request prior authorization from your doctor.

Your 2027 enrollment timeline — when to do what

New Medicare Advantage and Part D formularies (drug lists) drop in mid-September. Here's the step-by-step calendar:

How to check whether your medications are covered by your new plan

The formulary is the plan's official list of covered drugs, organized by tier (how much you pay). You MUST check it before you enroll. Here's how:

Prior authorization and step therapy: what they mean and how to handle them

Many plans restrict coverage of certain drugs to control costs. The two most common restrictions are prior authorization (PA) and step therapy (ST).

What to do if your new plan requires PA or ST for your current drug:

1. During AEP (Oct 15 – Dec 7), ask your doctor or their office staff to submit a prior authorization request to your new plan. The request usually takes 5 minutes and can be done by phone or fax.
2. Have your doctor include clinical notes explaining why you need THIS drug: "Patient was stable on this medication for 5 years," or "Patient has a contraindication to the step-therapy alternative." Plans often approve exceptions with a clinical justification.
3. If the plan says no initially, ask for an appeal. Your doctor can file an expedited (72-hour) appeal if the denial would harm your health. Don't give up — many first denials are overturned on appeal.
4. If PA isn't approved by January 1, you still get your transition fill (30 days) so you don't run out while the appeal is pending.

Transition fills: your 30-day safety net when coverage changes

The transition fill is Medicare's built-in safety net when you switch plans. Here's what it is and how to use it:

Definition: On January 1, when your new plan starts, if your new plan doesn't cover a medication you were taking on your old plan — or requires prior authorization that isn't approved yet, or restricts it with step therapy — your new plan MUST automatically provide a one-time, 30-day supply of that medication. The plan pays for it (usually at a low cost), and you can fill it at any pharmacy, even if the pharmacy is out-of-network.

How it works in practice:

1. On January 1, go to your pharmacy with your new insurance card and ask to fill your medications as usual.
2. If the pharmacist says "This drug isn't covered by your new plan," tell them you want a transition fill. The pharmacist submits the request to your new plan (this is automatic, but you can ask to confirm).
3. You'll get a 30-day supply at the new plan's cost (usually $0 to $10). That gives you a month to get prior authorization approved, request a formulary exception, or switch to a covered alternative with your doctor.
4. After the 30 days, you need a permanent solution: either the new plan approves prior authorization, or you switch to a covered alternative drug, or you pay out-of-pocket. The transition fill is a one-time bridge, not ongoing coverage.

Pharmacy networks: don't get stuck out of network on January 1

Each Medicare Advantage and Part D plan has a contracted pharmacy network. Your copays are lowest at in-network pharmacies. Out-of-network prescriptions often cost much more or aren't covered at all (with rare exceptions like transition fills).

Before you switch plans, confirm your pharmacy is in-network:

1. Call your current pharmacy and ask: "Will you still be in-network with [New Plan Name] starting January 1, 2027?"
2. If yes, great. You're set — no changes needed.
3. If no, or if the pharmacy isn't sure, find an in-network pharmacy near you using the plan's website or by calling the plan's customer service number. Then ask your doctor whether any of your current medications have a generic or therapeutic equivalent available at that new pharmacy.
4. Mail-order and 90-day supplies: Some plans offer mail-order pharmacies or 90-day supplies at retail locations. These often have lower copays if you fill more frequently than usual. Ask about them during AEP.

How to estimate what your medications will cost in 2027

Copays vary wildly between plans. A drug might be $15 in one plan and $60 in another. Here's how to compare costs across your full medication list:

Requesting a formulary exception when your preferred drug isn't covered

If your new plan's formulary doesn't include the drug your doctor prefers, your doctor can request a formulary exception — an approval to cover a drug that's normally not on the plan's list or to move it to a lower copay tier.

When to request an exception:

• Your drug isn't on the formulary at all.
• The plan requires step therapy and your doctor says the step-therapy drug won't work for you.
• The copay is much higher than you expected and cost is a barrier to taking your medication.

How to request one:

1. Ask your doctor's office to contact your new plan's exceptions line (usually a fax or phone number on the plan's website).
2. Your doctor provides clinical justification, such as: "Patient has a contraindication to the preferred drug," "Patient was stable on this medication for 5 years," or "Patient tried the step-therapy drug and it caused an adverse event."
3. Timeline: Standard exception decisions take up to 72 hours. Expedited requests (when there's a medical urgency) take up to 24 hours.
4. If denied, your doctor has the right to appeal. Many first denials are overturned on appeal, especially if clinical notes are strong.

Special Enrollment Period: if your current plan is ending

If your current Medicare Advantage or Part D plan is being discontinued (like Presbyterian in New Mexico in 2027), or your plan is leaving your county, you get a Special Enrollment Period (SEP) — a window to switch plans outside the normal AEP.

What you need to know:

• Timing: Usually 2 months from the date your plan sends you a discontinuation notice.
• Options: You can switch to any other Medicare Advantage plan, any Part D plan (if you're on Original Medicare), or back to Original Medicare.
• No waiting period: Unlike AEP, there's no wait — your new plan can start as soon as your old plan ends (usually January 1 if your notice comes in late fall).
• Don't miss it: If you miss your SEP deadline, you'll have to wait for the next AEP (Oct 15 – Dec 7, 2026).

Mistakes that create medication gaps

Free help in New Mexico when you get stuck

If prior authorization is delayed, you can't find a covered pharmacy, or you're confused about your transition fill, you don't have to figure it out alone.