Medicare Enrollment Windows in Texas: Which One Applies to You
Medicare has several enrollment periods and they do different things. Using the wrong one is how people end up locked into a plan for a year or paying a penalty they cannot remove.
Initial Enrollment Period
Seven months long, centered on your 65th birthday month: three months before, the birthday month, and three months after. This is when you first sign up for Part A and Part B, and it is the one with the permanent penalty attached if you miss it without other creditable coverage.
Enrolling in the first three months gets coverage started the month you turn 65. Enrolling later in the window pushes the start date back.
Annual Enrollment Period
October 15 through December 7 every year. This is the window most people mean when they say open enrollment. You can join, switch or drop a Medicare Advantage plan, and join, switch or drop a Part D plan. Changes take effect January 1.
Note this is a completely separate calendar from ACA Marketplace open enrollment, which runs on different dates. Texas residents who have shopped Marketplace coverage before often assume the dates carry over. They do not.
Medicare Advantage Open Enrollment
January 1 through March 31. If you are already in a Medicare Advantage plan, you get one chance in this window to switch to a different Advantage plan or drop back to Original Medicare with a standalone Part D plan.
It is a narrower window than the fall one: you cannot use it to switch from Original Medicare into an Advantage plan, and you only get one change.
Special Enrollment Periods
Certain events open a window outside the normal calendar: moving out of your plan's service area, losing employer coverage, your plan leaving your county, or qualifying for Extra Help. Moving between Texas counties can itself trigger one, since Medicare Advantage service areas are county based.
The Medigap six-month window is separate from all of these and is the one people most often lose without noticing. It starts when your Part B starts, runs six months, and does not come back.
Why the fall window deserves more than a glance
Plans change their formularies, networks and cost sharing every year, and your health changes too. Treating the fall window as a genuine annual review rather than a formality is the difference between a plan that fits and one that fit two years ago.
Moving within Texas can open a window
Medicare Advantage and Part D service areas are county based, so moving between Texas counties can trigger a Special Enrollment Period even if you have not left the state. Someone relocating from Harris, Dallas, Bexar and Tarrant counties to a smaller county may find their current plan is not offered at the new address at all.
The window generally runs from the month before your move through two months after, and it is easy to let it pass during the chaos of moving. Notifying your plan of the address change is what starts the clock.
Which window does what
Only the Initial Enrollment Period lets you sign up for Part A and Part B for the first time without penalty, outside a Special Enrollment Period.
Only the Annual Enrollment Period lets you move from Original Medicare into a Medicare Advantage plan.
Only the six-month Medigap window guarantees you a supplement policy regardless of health. It is the only one of these that never comes back, which is why it deserves the most attention and usually gets the least.
Related guides
Talk it through with a licensed Texas agent
Medicare choices are easier to make out loud than on paper. A licensed Texas agent can compare what is actually available in your county at no cost to you.