Medicare Enrollment Periods Explained: Every Window and Date

Let's set the stage

Most Medicare mistakes are timing mistakes. People sign up late and pay a penalty for life, or they miss the one window where a Medigap company has to accept them without health questions. The windows are not complicated once you see them side by side. Here they are.

All Medicare enrollment periods at a glance

Sources: Medicare.gov, Joining a plan and When does Medicare coverage start.

Initial Enrollment Period: your first and best window

Your IEP is built around your 65th birthday month. If your birthday is in June, your IEP runs from March 1 through September 30. Premium-free Part A starts the first of your birthday month (or the month before, if your birthday falls on the 1st). For Part B, Medicare.gov says signing up before your birthday month starts coverage the month you turn 65, while signing up during your birthday month or the three months after starts coverage the following month. Here's the thing: signing up early in the window is the easy way to avoid a gap.

If you already get Social Security retirement benefits, you are usually enrolled in Part A and Part B automatically, and your card arrives in the mail before your birthday month. Our how to enroll guide covers the steps if you are not.

The 8-month Special Enrollment Period for people who kept working

If you or your spouse have group health coverage from current employment, you can delay Part B and sign up later without a penalty. Medicare.gov says the window runs until 8 months after the group coverage or the employment ends, whichever comes first. If you sign up while still covered or in the first full month after it ends, you can ask for Part B to start up to 3 months later. COBRA does not count as current employment coverage, so do not let COBRA run out the clock.

General Enrollment Period: the catch-up window

If you missed your IEP and do not qualify for a Special Enrollment Period, you can sign up from January 1 to March 31. Coverage starts the month after you sign up. You may owe a Part B late enrollment penalty of 10% for each full 12-month period you could have had Part B but did not. See late enrollment penalties.

Open Enrollment: October 15 to December 7

This is the window most people know from TV. Anyone with Medicare can join, switch or drop a Medicare Advantage plan or a Part D plan, and the change takes effect January 1. For 2027 coverage, the window is October 15 through December 7, 2026. Plans change every year, so read the Annual Notice of Change your plan mails in September. For 2027 in Utah, the CMS landscape file shows 33 non special needs Medicare Advantage plans across the state and 8 stand-alone Part D plans, and the Part D out-of-pocket cap rises to $2,400. See Medicare Open Enrollment 2027 dates and Part D changes for 2027.

Medicare Advantage Open Enrollment: January 1 to March 31

If you are in a Medicare Advantage plan on January 1, you get one more chance. You can switch to a different Medicare Advantage plan or drop back to Original Medicare and pick up a stand-alone Part D plan. You can make one change during this window. It does not let someone on Original Medicare join Medicare Advantage for the first time.

Special Enrollment Periods

Life does not wait for October. Medicare.gov lists events that open a Special Enrollment Period, including:

• Moving to a new address outside your plan's service area, or into or out of a nursing home
• Losing other coverage, such as job-based coverage or Medicaid
• Getting Medicaid or qualifying for Extra Help with drug costs
• Your plan leaving your area or ending its contract with Medicare

Each SEP has its own length and rules. Call us before you assume you qualify.

Medigap open enrollment: the window people miss

Your Medigap open enrollment lasts 6 months and starts the first month you have Part B and are 65 or older. During it, a company selling Medigap plans in Utah has to sell you any policy it offers, at its best available rate, regardless of health. After it closes, companies can ask health questions and can decline you. If you think you may ever want a Medigap plan, this window deserves real thought. Our answer on switching from Medicare Advantage to Medigap in Utah covers what happens later.

Common Special Enrollment Periods at a glance

Source: Medicare.gov, Special Enrollment Periods. Each event has its own timing rules, so check the exact window before you rely on it.

Here's the thing. A move inside Utah can count. Plan choices change a lot from county to county here: the 2027 CMS landscape shows 28 Medicare Advantage plans in Salt Lake County but 6 in Sanpete and none outside special needs plans in Wayne. If you move from Salt Lake to Sanpete County, your current plan may not be offered at the new address.

A quick example

Linda in Sandy turns 65 on August 14 and is retiring from a job with coverage at the end of July. Her IEP runs May 1 to November 30. If she signs up for Part B in May, June or July, her coverage starts August 1. Her Medigap open enrollment would then run August 1 through January 31. If she wants Medicare Advantage instead, she can choose a plan in her IEP with coverage starting August 1.

Everything Senior Insurance is a licensed insurance agency in Utah. We are not connected with or endorsed by the U.S. government or the federal Medicare program.

Updated October 26, 2026 by the Everything Senior Insurance Data Desk.