Newsroom · Grand Junction and Mesa County

Is Aetna Leaving Medicare Advantage in Colorado for 2027?

Aetna is staying in Mesa County, but half of its Colorado county map is gone, and three of its six Grand Junction plans end December 31. Here is what the CMS 2027 file shows plan by plan, what the letter in your mailbox means, and the one thing an HMO-POS member needs to check about the new HMO.

Medicare On Main Data Desk

Published October 4, 2026 · 9 min read · Reviewed by Brian Penner

The short answer is no, Aetna is not leaving Colorado, and yes, it is leaving a lot of Colorado. Both are true at once, and the version that matters is the one for your county and your plan. I pulled Aetna's rows out of the CMS 2026 and 2027 landscape files on October 4 and compared them by contract-plan ID, which is the only way to do it, because carriers reuse plan names under new numbers every year. What follows is that comparison for Mesa County first, the rest of the Western Slope second, and the state third. Nothing here is a judgment of Aetna; plans entering and leaving each fall is how this market works, and this post explains the business reasons behind it.

Mesa County: every Aetna plan, 2026 and 2027

General Medicare Advantage plans only; the Dual Special Needs Plans are further down. Premium is the consolidated Part C plus Part D monthly premium, on top of Part B. Cap is the in-network maximum out-of-pocket. The star is the plan's 2026 overall rating; 2027 ratings are blank in the file until CMS publishes them this month.

Source: CMS CY2027 landscape file compared against the CY2026 file by Contract Plan ID, October 4, 2026. Plan names and figures are reproduced from the public file for information and do not imply endorsement of any company or plan.

Three things in that table deserve a second look. First, the two plans that are gone were the HMO-POS plans, and the plan that is new is a plain HMO. An HMO-POS lets you get some covered services out of network at a higher cost; a plain HMO generally does not, outside emergencies (Medicare.gov). If you used that flexibility this year, for a specialist in Denver or a winter in Arizona, the new plan is not a like-for-like swap. Second, every continuing Aetna drug plan moves to the $700 Part D deductible, up from $615, and the 2027 Part D out-of-pocket cap is $2,400. Third, the PPO caps rose: Signature from $6,750 to $7,150 and Value Care from $5,500 to $7,150, even as Value Care's premium fell. A lower premium beside a higher cap is a trade, not a discount.

Crosswalk or non-renewal? Read your letter

Federal regulation defines a crosswalk as the movement of enrollees from one plan to another under a contract between the carrier and CMS, and says that "except as described in paragraph (c) of this section, crosswalks are prohibited between different contracts or different plan types (for example, HMO to PPO)" (42 CFR § 422.530). The ending HMO-POS plans sit under contracts H3931 and H4711; the new HMO sits under H5593, a contract with no Colorado row in 2026. The rule's exceptions include a case where contracts under the same parent company are consolidated into one surviving contract, so a move is not impossible, but the public file cannot tell you whether it happened to you. Your mail can:

• Your Annual Notice of Change (due by September 30) says you will be in Aetna Medicare Signature (HMO) on January 1, 2027. You were moved. You are not losing coverage and you were not returned to Original Medicare, so you do not get the discontinued-plan Special Enrollment Period or the Medigap guaranteed-issue right described below. What you do get is a network to verify, a $700 drug deductible to price, and the ordinary October 15 to December 7 window to pick something else if the HMO is not the right fit (Medicare.gov on the ANOC).
• You received a separate notice, dated around October 2, saying your plan will not be offered in 2027. You were not moved. Federal rules require that letter by mail at least 90 days before the plan ends (42 CFR § 422.506), and Medicare.gov describes it as the notice that you need to choose new coverage (Medicare.gov). If you do nothing, you are in Original Medicare on January 1 with no drug plan and no out-of-pocket cap. Keep this letter; it is your proof for the Medigap door.

If you have both letters and they seem to contradict each other, call the number on your card and ask one question: "Am I enrolled in an Aetna plan for 2027, and which contract-plan ID?" This post walks through the three letters line by line.

Delta, Montrose, and the rest of the Western Slope

Source: CMS CY2026 and CY2027 landscape files, general MA-PD rows (medical-only plans noted in parentheses; Special Needs Plans counted separately).

Delta County is the sharper story. Aetna's Signature PPO, which was sold in Delta this year, is listed for Mesa and Montrose in 2027 but not Delta, so a Delta member of that plan is in the "plan stays, but leaves your county" case, which is treated as a non-renewal for that member. Aetna's only remaining Delta drug plan is Value Care (PPO) at $18.40 with a $7,150 cap. Delta's whole shelf went from 15 plans to 7, which the Montrose and Delta post lists in full. Garfield and Rio Blanco never had an Aetna plan, and Garfield still has no general Medicare Advantage plan at all.

Sources: CMS landscape files · CMS Medicare Monthly Enrollment, Mesa County, June 2026.

The statewide picture: 17 counties kept, 16 counties left

Aetna's Colorado footprint went from 122 plan-county listings across 33 counties in 2026 to 42 across 17 in 2027. The counties that keep an Aetna drug plan are Adams, Arapahoe, Boulder, Broomfield, Delta, Denver, Douglas, El Paso, Fremont, Grand, Jefferson, La Plata, Larimer, Mesa, Montrose, Pueblo, Weld. The counties with none for 2027 are Archuleta, Clear Creek, Conejos, Crowley, Custer, Elbert, Gilpin, Huerfano, Jackson, Las Animas, Lincoln, Morgan, Park, Saguache, Teller, Washington. If you live in one of the second group, every Aetna member there received a non-renewal notice, and the Medigap and Special Enrollment doors below are open to you. If you have family in Teller or Park County on an Aetna plan, this is worth a phone call.

This fits a national pattern that was announced long before the file came out. In 2025 and again this year, the large carriers told investors they would trim plans and counties where the math no longer works; Humana said so in July, and Mesa County's whole shelf shrank from 16 drug plans to 10 as a result. Aetna's share of that shrinkage is one plan: four Aetna drug plans in 2026, three in 2027.

If you were NOT moved: your three doors

1. Another Medicare Advantage plan — from Aetna or any other carrier in Mesa County — chosen during the October 15 to December 7 Annual Enrollment Period so it starts January 1 (Medicare.gov). All 10 drug plans are listed with their 2026 numbers in the Mesa County 2027 post. Check your doctors at St. Mary's, Community Hospital and your clinic first, your drug list second, the cap third, the premium last.
2. Original Medicare plus a Medigap policy plus a stand-alone drug plan. Per Medicare.gov, when your plan leaves Medicare or stops serving your area and you return to Original Medicare, you may buy Medigap Plan A, B, D, G, K or L with no health questions, applying as early as 60 days before and no later than 63 days after your coverage ends — November 1, 2026 through March 4, 2027. Plans C and F are limited to people who were Medicare-eligible before 2020. The Colorado guaranteed-issue post has the details; Colorado has eight stand-alone drug plans for 2027.
3. Original Medicare plus a drug plan, no Medigap. Lowest premium, no network, but no annual cap on your 20% share. Reasonable for some; most people in their 70s and 80s should price it before accepting it.

Miss December 7 and a discontinued plan still gives you a Special Enrollment Period from December 8 through February 28 to pick another Advantage plan (42 CFR § 422.62), but a plan chosen in January starts February 1, leaving January in Original Medicare with no drug coverage. Treat the SEP as a safety net, not a plan. Here is what doing nothing actually costs.

If you WERE moved into the new HMO: three checks

1. The network, doctor by doctor. Your HMO-POS had an out-of-network option; a plain HMO generally covers only emergencies outside its network. Confirm every doctor, both Grand Junction hospitals and any Front Range specialist against the 2027 directory for contract-plan ID H5593-007 specifically, not "Aetna." How to check a 2027 network before you enroll.
2. The drug deductible. $615 becomes $700. Look at which of your drugs sit on tiers subject to the deductible; many plans exempt the lowest generic tiers, and the Evidence of Coverage says which. The drug-check post shows how.
3. Prior authorizations and the extras you used. An approval on your 2026 plan does not automatically travel to a plan under a new contract, and a dental, hearing or over-the-counter allowance you relied on may differ. Prior authorization on a new plan covers what to do in December.

If the HMO is not the right fit, you still have the ordinary October 15 to December 7 window to choose any plan in Mesa County, and the January 1 to March 31 Medicare Advantage Open Enrollment Period for one more switch after that. What you do not have, as a moved member who stayed in Medicare Advantage, is the guaranteed-issue Medigap right; that belongs to people returned to Original Medicare. If Medigap is where you want to end up, say so before December 7, and we will walk through the underwriting path with you.

Dual-eligible members: a smaller version of the same story

Aetna's Mesa County Dual Special Needs Plans changed too. Dual Extra Care (H3931-175) and Full Dual Care (H3931-196) continue with their premiums dropping to $0, Dual Care (H4711-012) is not in the 2027 file, and a new Full Dual Extra Care (H5593-005) appears at $0. If you have Medicare and Health First Colorado and were in the ending plan, your letter follows the same rules above, and your Medicaid eligibility is a separate question that the plan change does not touch. The D-SNP post explains how the two programs fit together.

The calendar from here

What I would do this week

1. Find your letters and sort yourself into a group. ANOC that names Signature (HMO) for January 1 = moved. Separate notice that the plan will not be offered = non-renewed. Not sure = call the number on your card and ask for your 2027 contract-plan ID.
2. Write down every doctor, every prescription and your pharmacy. Mesa County runs about 26.6% high blood pressure and 8.1% diabetes among adults per CDC PLACES; for most of the people reading this, the drug list is the comparison.
3. Non-renewed and leaning toward Medigap? The window opens November 1. There is no reason to wait for December, and no reason to let anyone rush you before November either.
4. Moved into the HMO? Verify the network before Thanksgiving, while there is still time to change your mind by December 7.
5. Ignore the phone calls. A plan ending is a magnet for marketing. No legitimate agent needs your Medicare number to "verify" anything, and nobody can enroll you in a 2027 plan before October 15.

How we know all this: the Medicare On Main Data Desk frames every article with public data — here, the CMS CY2026 and CY2027 landscape files compared by Contract Plan ID on October 4, 2026, CMS's county enrollment data, CDC PLACES for Mesa County, and the federal rules and Medicare.gov pages on plan crosswalks, non-renewal notices, HMO-POS plans, enrollment periods and Medigap guaranteed-issue rights. We do not know which Aetna members were moved and which were not; only your letter and your plan do. 2027 Star Ratings are not yet published and none are stated. Medicare On Main is a licensed independent insurance agency. We do not offer every plan available in your area. Any information we provide is limited to the plans we do offer in your area. Please contact Medicare.gov or 1-800-MEDICARE to get information on all of your options. Not connected with or endorsed by the U.S. government or the federal Medicare program. Mentioning a carrier is not an endorsement or a criticism; plan availability is a fact of the market. This is education, not advice; confirm your plan, costs and eligibility with a licensed agent or Medicare.gov.