Medicare Open Enrollment Starts October 15: What Network Changes Mean for Your Credentialing

How Does Medicare Open Enrollment Affect Provider Credentialing?

As of October 2026, Medicare Open Enrollment runs from October 15 through December 7, giving beneficiaries the opportunity to switch between Medicare Advantage plans or move back to Original Medicare for 2027 coverage. For providers, this enrollment window signals a period of significant network restructuring by MA plans, which means credentialing status with specific payers can shift. Providers who are not actively enrolled and credentialed with the plans their patients choose risk losing patient volume starting January 1, 2027.

• Network shifts are accelerating: CMS projects approximately 900,000 fewer Medicare Advantage enrollees in 2026, and multiple plans are exiting markets or narrowing networks for 2027, making panel participation verification critical.
• Directory accuracy now has teeth: CMS now requires MA plans to submit provider directory data to the Medicare Plan Finder, and beneficiaries who rely on incorrect directory data gain special enrollment period rights to switch plans.
• Credentialing lead times do not wait: Payer credentialing takes 60 to 120 days. Providers who wait until January to enroll with new plans will miss the first quarter of 2027 patient volume entirely.

What CMS Announced for 2027 Coverage

On October 1, 2026, CMS released updated data confirming that Medicare Open Enrollment for 2027 coverage runs from October 15 through December 7, 2026. Access to MA plans remains broad, with more than 99% of beneficiaries having access to at least one plan and 97% having access to 10 or more plan choices. The total number of available MA plans nationally is expected to shift from approximately 5,553 in 2026 to 5,532 in 2027.

Behind those headline numbers, several changes are directly relevant to provider credentialing. CMS loosened marketing restrictions on insurance agents and brokers starting October 1, 2026, which means more aggressive outreach to beneficiaries during open enrollment. CMS also removed the requirement that a provider network change be “significant” to trigger a special enrollment period. Under the new rule, any network change that affects a beneficiary gives them the right to switch plans outside the normal enrollment window.

We see the downstream effect of these changes every year at Contracting Providers. When MA plans restructure their networks, providers who assumed their credentialing was stable discover they have been dropped from a panel or that a plan covering a large share of their Medicare patients has exited their market. The time to verify panel status is now, not after patients have already switched plans. For providers who need a broader understanding of how insurance contracts work between payers and providers, our guide covers the key terms and structures.

Which Providers Need to Act Before Open Enrollment Ends?

Every provider who sees Medicare Advantage patients needs to verify their credentialing status before January 1, 2027. But certain provider types face higher risk during this enrollment cycle.

Providers in markets where MA plans are exiting or merging are the most exposed. When a plan exits a market, its enrolled providers lose that panel entirely. The beneficiaries who were on that plan will select a new plan during open enrollment, and if the provider is not credentialed with the plan those patients choose, the patient relationship may end.

Providers who recently expanded to new locations face a different version of the same problem. A new practice location needs its own credentialing with each payer. If you opened a second office in 2026 but only credentialed it with two or three plans, you are leaving patient volume on the table during the busiest enrollment period of the year.

Behavioral health providers, rehabilitation therapists, and specialists in high-demand areas are also at elevated risk because MA plans have been selectively narrowing specialty networks while maintaining broad primary care panels. The narrowing is often not announced publicly. The provider simply does not appear in the plan directory for the following year.

Why Provider Directory Accuracy Matters More in 2027

Starting with the 2027 plan year, CMS requires Medicare Advantage plans to submit provider directory data for display on the Medicare Plan Finder at Medicare.gov. This means beneficiaries shopping for plans during open enrollment can now check whether their doctor is in-network before they choose a plan. Previously, this information was only available on individual plan websites, which varied widely in accuracy.

The credentialing connection is direct. If your practice information in a payer’s directory is outdated, incorrect, or missing, beneficiaries will not see you as an option when they compare plans. They will choose a plan where their preferred providers appear. The result is lost patient volume that you may not even realize is happening until claims stop coming in.

One pattern we see frequently is providers whose CAQH profile has outdated address or specialty information. Since many payers pull directory data from CAQH, a stale profile can cascade into inaccurate listings across multiple plans. Updating your CAQH profile before open enrollment is one of the highest-impact things you can do to protect your panel participation.

At Contracting Providers, we handle credentialing verification and payer enrollment across 40 or more states. If you are not sure which plans you are credentialed with or whether your directory listings are current, our team can run a full audit and file corrections before open enrollment closes.

What Providers Should Do Before December 7

Open enrollment closes December 7, 2026. Here is the action list.

1. Pull your current payer roster. List every Medicare Advantage plan you are currently credentialed with. Contact each plan or check your credentialing portal to confirm your participation status for the 2027 plan year. Do not assume last year’s status carries forward automatically.
2. Verify your directory listings. Check your practice name, address, phone number, specialty, and accepting-new-patients status in every MA plan directory where you are listed. Errors in any field can cause you to be invisible to beneficiaries shopping on the Medicare Plan Finder.
3. Update your CAQH profile. Complete your CAQH attestation if it is overdue. Update addresses, specialty designations, and group affiliations. Many payers pull directory data directly from CAQH, so a current profile is the fastest way to fix directory errors across multiple plans at once.
4. Identify new plans entering your market. Check the CMS Medicare Plan Finder for new MA plans available in your service area for 2027. If a new plan is entering your market with competitive benefits, consider enrolling now so you can see those patients starting in January.
5. Start credentialing applications for any gaps. If you identify a plan you are not credentialed with, start the application immediately. Credentialing takes 60 to 120 days, so applications filed in October may not clear until Q1 2027 at best. Applications filed in December will not be active until March or later.
6. Confirm your Medicare enrollment is active. Medicare Advantage credentialing requires active Medicare enrollment as a prerequisite. If your PECOS enrollment has any pending issues or holds, resolve them first. Our guide on what a CAQH number is and why providers need one explains how CAQH and Medicare enrollment connect.

Credentialing Mistakes During Open Enrollment

The most common mistake we see at Contracting Providers is assuming that credentialing is a one-time event. Providers complete their initial credentialing and then treat it as done. But payer networks change every year. Plans exit markets, merge with other plans, or restructure their provider panels. A provider who was in-network with a plan in 2026 may not be in-network with the successor plan in 2027 unless they actively confirm or re-credential.

Another frequent mistake is ignoring re-credentialing timelines. Most payers require re-credentialing every two to three years. If your re-credentialing cycle falls during Q4, and you miss the deadline because your office is busy with year-end operations, you can be silently dropped from the panel. The payer does not always send a warning. They simply remove you from the directory for the next plan year.

A third pattern involves group practices that add new providers without enrolling them with every plan the group participates in. The new provider sees patients, but claims are denied because that individual provider is not credentialed with the specific plan the patient selected during open enrollment. The revenue gap can run for months before anyone catches it.

In-House vs. Outsourced Credentialing During Open Enrollment

Q4 is the worst time to handle credentialing in-house because it overlaps with the busiest clinical period of the year, year-end financial close, and the administrative load of processing annual insurance changes for your own staff. Adding a payer verification and credentialing project on top of that workload is how things fall through the cracks.

At Contracting Providers, we manage credentialing and payer enrollment as our core service. During open enrollment season, our team verifies panel status across all contracted payers, identifies directory errors, files corrections, and submits new credentialing applications where gaps exist. We do this across 40 or more states, for solo practitioners and multi-provider groups alike. Our first-time approval rate across all enrollment types runs approximately 94%, and we respond to every client inquiry within 24 hours.

For practices that want to handle verification themselves but need help with new applications or corrections, we also support one-off engagements. The key is starting before December 7, because everything filed after open enrollment closes is reactive rather than proactive.

Frequently Asked Questions

Next Steps

Start by pulling your current payer roster and confirming your participation status with each Medicare Advantage plan for the 2027 plan year.

Update your CAQH profile and complete any overdue attestations. Our CAQH ProView guide walks through the process step by step.

Schedule a free consultation with our credentialing team to run a panel verification audit before December 7.