Prior Authorization in 2027 Medicare Advantage Plans: What's Changing

If your Medicare Advantage plan approved your surgery, your infusion therapy, or your durable medical equipment this year, it's natural to assume that approval just carries forward into next year. It doesn't. Every plan resets its rules on January 1, and a service that sailed through prior authorization in 2026 can suddenly need a new request, or get denied outright, in 2027, even though nothing about your health has changed.

This is one of the most common and most confusing surprises in Medicare Advantage. Understanding why it happens, and what protections you actually have, can save you weeks of frustration in January and February.

Why Approved Care Doesn't Automatically Carry Into 2027

Medicare Advantage plans set their prior-authorization criteria, coverage rules, formularies, and provider networks on a per-plan-year basis. All of it resets on January 1. A plan can keep the same name, the same premium, and even the same benefits summary, and still change which services require prior authorization, which drugs are covered, and which criteria a request has to meet.

That means a service that was approved and covered in 2026 can require prior authorization, or be denied, in 2027 under the exact same plan, with no change in your medical condition. This isn't a mistake or a sign your plan is targeting you. It's simply how the annual plan-year structure works. If you want a fuller walkthrough of how prior authorization functions in Medicare Advantage generally, our prior-authorization explainer covers the basics in more depth.

Where to Actually Find Your Plan's 2027 Rules

Many people check their plan's provider directory to see what's covered, but the directory only tells you which doctors and facilities are in network. It doesn't tell you what needs prior authorization or what the coverage criteria are.

Instead, look in two places:

• The Evidence of Coverage (EOC): this is your plan's full rulebook for the coming year, spelling out covered benefits, cost-sharing, and general rules.
• The plan's separately published prior-authorization list: most plans publish this as its own document, distinct from the EOC and the directory, listing exactly which services and drugs require prior approval.

Both of these are specific to the plan year. The 2026 version does not apply once January 1, 2027 arrives.

When These Documents Become Available

Your plan is required to send you an Annual Notice of Change (ANOC) that flags what's changing for the coming year, including cost, formulary, network, and prior-authorization changes. For 2027 coverage, that notice must reach you no later than September 30, 2026. The ANOC is a summary of changes, not the full rulebook.

The complete, updated Evidence of Coverage and prior-authorization list for the new plan year are published alongside or shortly after the ANOC, ahead of the Annual Enrollment Period. That period runs October 15 through December 7, 2026, with any changes taking effect January 1, 2027. If you don't actively choose a different plan during that window, doing nothing is not neutral: you're generally renewed into the same plan, but under its new plan-year terms, not the terms you had this year.

Why Denials Spike in January and February

Every year, prior-authorization denials tend to rise in the first couple of months after the plan year turns over. There isn't a single verified figure for how much they rise, but the pattern is consistent and it makes sense once you understand what's happening behind the scenes.

• Criteria reset on January 1, so a request that would have been approved under 2026 rules may not meet the 2027 criteria.
• Standing approvals from the prior year don't automatically carry over into the new plan year, even for ongoing treatment.
• Staff at both the health plan and your doctor's office are often still working from habits and paperwork built around the old rules, which can lead to requests being submitted or processed incorrectly in the first weeks of the new year.

The result is a predictable wave of new-year denials, many of them affecting people who did absolutely nothing differently. If you get one of these denials, it doesn't mean your care isn't medically necessary. It often means the paperwork hasn't caught up with the new plan year yet.

Continuity of Care: What Protection You Actually Have

CMS does build in some protection for people who are mid-treatment when the calendar flips or when they switch plans, but it's important to understand exactly what it covers.

First, if a prior authorization was already approved for a specific course of treatment, that approval stays valid for as long as the treatment remains medically necessary. An approval in hand doesn't expire in the middle of an ongoing course of care.

Second, if you join a new Medicare Advantage plan while you're already in an active course of treatment, meaning you're actively seeing the provider and following the treatment plan, the plan must give you a minimum transition period of at least 90 days. During that window, the plan is not allowed to disrupt your care or demand reauthorization. This protection applies whether you're new to that plan or new to Medicare altogether, and it applies even if your provider is out of network.

That "at least 90 days" language matters. Ninety days is a floor, not a fixed length, and some situations carry a longer minimum. Don't assume your protection ends exactly on day 91. The safest move is to ask your new plan, in writing, exactly how long your existing approval carries over. Get a specific answer rather than relying on assumptions.

What Continuity of Care Does Not Cover

These protections apply to active, ongoing courses of treatment and to genuine plan transitions. They don't mean every service you received in 2026 is guaranteed to be treated the same way in 2027 if your treatment has ended, changed, or was never part of a continuous course of care. That's exactly why checking your plan's current-year documents matters, even if last year went smoothly.

What to Do Before January

You don't have to wait for a denial letter to find out where you stand. A little homework in the fall can prevent a lot of stress in January.

• List every ongoing treatment, therapy, medication, and piece of equipment you currently use or receive, including anything that required prior authorization this year.
• Contact your plan directly and ask whether the 2027 prior authorization for each item is already on file, or whether a new request needs to be submitted.
• Get the answer in writing. A verbal assurance from a customer service line is hard to prove later if a denial shows up in January.
• Review your ANOC and the new prior-authorization list as soon as they're available, rather than assuming last year's rules still apply.

Doing this before the new plan year starts gives your doctor's office time to submit any needed paperwork before treatment is due, instead of scrambling after a denial arrives.

If You're Denied Anyway

If a service you expected to be covered gets denied in the new plan year, you still have the right to appeal. Your denial will arrive as a Notice of Denial of Medical Coverage or Payment, also called an Integrated Denial Notice. Read it carefully for your specific appeal deadline and instructions, since Medicare Advantage Level 1 appeals must generally be filed within 65 calendar days from the date on the notice. Appealed Medicare Advantage prior-authorization denials are overturned often enough that giving up too quickly is a mistake; a 2024 KFF analysis found that roughly 80% of appealed prior-authorization denials were overturned, though only a modest share of denials are ever appealed in the first place. If your care was working for you in 2026 and nothing about your condition has changed, that's exactly the kind of evidence worth including in an appeal. Our appeal letter guide walks through how to structure that request.

Because dates, plan rules, and coverage details can shift, always confirm current information for your specific situation at Medicare.gov or by calling 1-800-MEDICARE before you rely on it.

Already read it? A quick review helps the next person find it.

This article is general education, not legal or medical advice. Medicare rules, deadlines, and dollar amounts change; confirm the current details for your situation at Medicare.gov or by calling 1-800-MEDICARE. MedicareClaimDenied.com is not affiliated with or endorsed by Medicare, CMS, or any insurer.