Guide

The December window: changing your Medicare posture

Summary

Medicare lets you change your participation status once a year, during an annual enrollment window that runs in the late fall and closes at year end, with the change taking effect on January 1. Your MAC administers the window, publishes its exact open and close dates, and processes the CMS-460 participation agreement. Outside that window, your status stays put until the next one.

By Gale Editorial · Updated 2026-07-26. Every figure cited to a dated source. How we write.

What Medicare participation actually is

Your Medicare participation status is a yearly commitment about assignment — whether you agree, in advance, to accept Medicare's approved amount as payment in full on every claim. A participating clinician accepts assignment on all Medicare claims; a non-participating clinician can decide case by case and, within limits, bill the patient more. Medicare claims and provider enrollment are administered regionally by a Medicare Administrative Contractor, or MAC, and CMS publishes which one serves your state 1Ref 1Centers for Medicare & Medicaid Services (2026).Medicare Administrative Contractors.That Medicare claims and provider enrollment are administered regionally through MACs, and that CMS publishes which MAC serves each jurisdiction and handles the participation agreement.. The participation agreement itself is an enrollment document your MAC processes, which is why the timing rules below are set there, not by you. This is one leg of the broader participation, non-par, opt-out decision.

When the window opens

You can change your status during one annual enrollment window. It runs in the late fall and closes at year end, and a change you make in it takes effect the following January 1 — the same date the new Medicare fee schedule takes effect. The exact open and close dates are set each year and published by your MAC, so the reliable move is to read your own MAC's annual participation-enrollment notice rather than rely on last year's calendar 2Ref 2Novitas Solutions Medicare (2026).Novitas Solutions Medicare.That a MAC publishes the enrollment and participation workflows that bind its providers — including the annual participation-enrollment notice, its dates, and how each status is paid — as an example of reading your own MAC's published policy.3Ref 3Palmetto GBA (2026).Palmetto GBA.That a MAC publishes the jurisdiction-specific enrollment and participation-window guidance that binds providers in its states, cited alongside another MAC so a reader looks to whichever contractor serves them rather than a single portal.. Outside the window, your status holds until the next one, which is why this decision belongs on a recurring calendar rather than in your memory.

How you actually change it

The change is made by submitting or withdrawing the CMS-460 participation agreement through your MAC. You can do it electronically or on paper — the same pecos vs the paper 855 choice you faced at enrollment — though the participation agreement is its own form, separate from the 855i application that first put you in the program 2Ref 2Novitas Solutions Medicare (2026).Novitas Solutions Medicare.That a MAC publishes the enrollment and participation workflows that bind its providers — including the annual participation-enrollment notice, its dates, and how each status is paid — as an example of reading your own MAC's published policy.. Keep proof of what you filed and when. Because the effective date is fixed at January 1 and the window is narrow, a submission that bounces for a signature or a mismatched identifier can cost you the whole cycle, so file early enough to fix a rejection before the window closes.

What changes when your status flips

Switching status changes two things at once: how Medicare pays you and what you may collect from the patient. A participating clinician is paid directly on assignment for every claim; a non-participating clinician is reimbursed on a different basis and may bill the patient up to a capped limiting charge, collecting more of the fee up front. Your MAC's participation materials lay out exactly how each status is paid and what the patient owes 2Ref 2Novitas Solutions Medicare (2026).Novitas Solutions Medicare.That a MAC publishes the enrollment and participation workflows that bind its providers — including the annual participation-enrollment notice, its dates, and how each status is paid — as an example of reading your own MAC's published policy.. The money math — the size of that difference, and whether it clears the added billing friction — is the heart of the choice, and it deserves its own worksheet before you file anything.

Why the once-a-year rule shapes your planning

Because the window is annual, you cannot switch reactively when a bad quarter or a payer change makes you reconsider. A common practice among solo clinicians is to review the participation decision every autumn alongside the year's payer mix and Medicare volume, so any change is filed inside the window and takes effect cleanly on January 1. Treating it as a standing annual task rather than a one-time setup is what keeps you from being locked into a status that no longer fits for a full extra year. If you miss the window, the status you already have simply carries forward.

What this is not: opt-out and MIPS

Two things are easy to confuse with this decision. Opting out of Medicare is not the same as being non-participating: opt-out means leaving Medicare entirely and seeing beneficiaries under private contracts, a separate election with its own rules and its own timing. And MIPS participation is a different word altogether — it is a quality-program obligation, and whether it applies to you is something you check by NPI in the QPP participation lookup, where low-volume clinicians are excluded 4Ref 4Centers for Medicare & Medicaid Services (2026).Check Eligibility — QPP Participation Status.That MIPS participation is a distinct concept a clinician checks by NPI in the QPP participation lookup, where low-volume-threshold clinicians are excluded — not the same participation as the CMS-460 par status.. Neither shares this window's dates or mechanics, so keep the three decisions — participate, don't participate, or opt out — clearly apart in your planning.

Common questions

It is an annual window that runs in the late fall and closes at year end, with any change effective the following January 1. CMS sets the precise open and close dates each year, and your MAC publishes them in its participation-enrollment notice. Read your own MAC's current notice rather than assuming last year's dates, since they can shift from one cycle to the next.

The CMS-460 is the Medicare participation agreement — the form that records whether you accept assignment on all claims. You submit it to become participating, or withdraw it to become non-participating, through your MAC during the annual window. It is separate from the 855I enrollment application that first added you to Medicare, and it governs only your participation status.

Your current status carries forward unchanged into the next year. Participation is not something you re-elect every cycle; it renews by default. You only need to act inside the window if you want to switch — from participating to non-participating, or the reverse. Missing the window simply means your existing status continues for another full year.

No. A non-participating clinician is still enrolled in Medicare and still bills Medicare, just on a different payment basis with the ability to bill patients up to a limiting charge. Opting out means leaving Medicare entirely and seeing beneficiaries only under private contracts. They are separate elections with different rules, and confusing them can create serious billing problems.

No. MIPS is a separate quality program, and its use of the word participation is unrelated to your par or non-par status. Whether you are subject to MIPS depends on your volume and is checked by NPI in the QPP participation lookup, where clinicians under the low-volume threshold are excluded. The annual participation window does not change any of that.

Run your practice on Gale

The software is free. Gale earns one flat 3.5% all-in per paid transaction — only on transactions that actually pay. No subscription, no setup fee, no network cut.

Start or manage a practice →

References

1.Centers for Medicare & Medicaid Services (2026). Medicare Administrative Contractors. Centers for Medicare & Medicaid Services (CMS). link ✓That Medicare claims and provider enrollment are administered regionally through MACs, and that CMS publishes which MAC serves each jurisdiction and handles the participation agreement.
2.Novitas Solutions Medicare (2026). Novitas Solutions Medicare. Medicare Administrative Contractor portal. link ✓That a MAC publishes the enrollment and participation workflows that bind its providers — including the annual participation-enrollment notice, its dates, and how each status is paid — as an example of reading your own MAC's published policy.
3.Palmetto GBA (2026). Palmetto GBA. Medicare Administrative Contractor portal. link ✓That a MAC publishes the jurisdiction-specific enrollment and participation-window guidance that binds providers in its states, cited alongside another MAC so a reader looks to whichever contractor serves them rather than a single portal.
4.Centers for Medicare & Medicaid Services (2026). Check Eligibility — QPP Participation Status. CMS Quality Payment Program. link ✓That MIPS participation is a distinct concept a clinician checks by NPI in the QPP participation lookup, where low-volume-threshold clinicians are excluded — not the same participation as the CMS-460 par status.

https://www.gale.care/for-providers/mc-annual-participation-window · 4 sources. Competitor details are cited to dated public sources and maintained as they change; figures are estimates, not commitments. Synthetic demonstration.

← Back to for providers