Colorado alert · Medicare
If your Medicare plan sends you a letter this autumn, keep it
A canceled Advantage plan opens the one door into Medigap that Colorado otherwise keeps shut. The window is six months, not 63 days, and the letter is the proof you need to walk through it.
Tina Price, Founder & Benefit Advisor
Published August 17, 2026 · 3 min read · Figures checked

Colorado doesn't let you switch Medicare Supplement plans once a year. There's no birthday rule here and no anniversary window, and once your one six-month window at 65 has closed, a carrier is allowed to ask about your health and turn you down.
That's what makes the exceptions so valuable — and one of them arrives in the post.
If a Medicare Advantage plan cancels, isn't renewed, or stops being offered in your county, everybody on it gets a guaranteed issue right. A carrier can't decline you, can't charge you more because of your medical history, and can't refuse to cover something you already have. For somebody who has developed a condition since 65, this is the only way back to a supplement.
More Coloradans than usual may get one of these letters for 2027. Two large national carriers have told investors they're cutting Advantage plans, and which counties are affected here doesn't become public until October 1.
The number almost everyone gets wrong
Look up how long you have and you'll find 63 days.
That's the right answer to a different question. Colorado's regulation actually sets two windows, and which one you're in depends on whether you left or your plan did.
If your plan ended it — canceled, not renewed, or withdrawn from your county — you have six months from the day the coverage ends.
If you ended it — you chose to leave — you have 63 days afterwards, and the window also opens 60 days before you go, so you can be approved for the new policy before the old one stops.
Six months against 63 days isn't a rounding difference. If your plan was canceled in December and somebody tells you in March that you've missed it, they're working from the wrong half of the rule, and you actually have until roughly June.
The letter isn't paperwork about the door — it is the door
Colorado requires you to send evidence of the termination date with the application. Not on request, not afterwards. With it.
So the notice your plan mails you is the document that proves you're entitled to buy without health questions. People throw it away because it looks like every other piece of insurance mail, and then a right they still have becomes one they can't demonstrate.
Photograph it the day it arrives and send us the photograph. That's genuinely the whole task.
What you can buy, which isn't everything
A guaranteed issue right reaches a defined list rather than the full shelf. If you came to Medicare in 2020 or later, that list is Plan A, B, D, G — including the high-deductible version of G — K and L, from any carrier licensed here.
Plan N isn't on it, and that's worth knowing in advance, because N is a common landing spot in an ordinary conversation and it simply isn't available in this one. So if you'd settled on N, the door you're walking through doesn't open onto it. Plan G does, from any company, at that company's regular rate.
Two more windows, and nothing reminds you they're closing
Neither of these involves a letter, and both of them run twelve months.
If Medicare Advantage was the first coverage you ever chose on Medicare, you can leave within a year and buy any supplement policy from any carrier — no plan-letter list at all, which makes this the widest door in the whole regulation.
And if you dropped a Medigap policy to try Advantage for the first time, you can come back within the year and have your old policy back from the same carrier, assuming they still sell it.
After two years from that first enrollment, nothing counts as a trial any more. So if you started an Advantage plan last autumn, put month ten in your calendar rather than month twelve — applications take time, and the deadline doesn't care that yours is in the post.
One more trigger, and the sequence matters
Moving out of your plan's service area is on the list too. Which window applies depends on whether the plan ends your enrollment or you do, so it's worth calling before you move rather than after. That sequence is inside your control, and it decides which of the two clocks you're on.
What to do with all this
If anything arrives from your Medicare plan between now and December, open it, keep it, and tell us the date on it. We'll work out which window you're in and whether a door is open — and we'll say so plainly if the answer is that staying put is your better option.
No charge, no obligation, and a licensed advisor rather than a call center.
CMS-required disclaimer
We do not offer every plan available in your area. Currently we represent 7 organizations which offer 45 products in your area. Please contact Medicare.gov, 1-800-MEDICARE, or your local State Health Insurance Program to get information on all of your options.
This article is general information, not advice about a specific plan. Required disclosures.