Last Updated: October 11, 2026 Reading Time: 8 min

Medicare Open Enrollment opens Thursday, October 15, 2026. FEHB Open Season opens 25 days later, on November 9. For a federal or Postal annuitant with Medicare, the two windows overlap for four weeks, and the mail from both sides arrives at once. Each window controls a different set of decisions. Getting the jurisdiction wrong is how annuitants end up with a plan they did not choose, or without a plan they can never get back.

Quick Answers: Medicare Open Enrollment vs FEHB Open Season

Can I change my FEHB plan during Medicare Open Enrollment?

No. Medicare Open Enrollment, October 15 to December 7, covers Medicare Advantage and Part D elections only. Changing an FEHB plan or option generally requires Open Season (November 9 to December 14, 2026) or another qualifying enrollment opportunity. Annuitants may request cancellation or reduce enrollment type outside Open Season, subject to applicable child-coverage restrictions.

If I do nothing in either window, what happens?

Your FEHB enrollment continues into 2027 in the same plan and option, and your Medicare coverage continues, though your plan's terms and prices may change for 2027. Nothing in Medicare Open Enrollment touches FEHB, and an FEHB enrollment is not cancelled by inaction. The one thing a do-nothing annuitant should check is whether the plan was discontinued or restructured for 2027. See what happens when an FEHB plan is discontinued.

Do I pick an FEHB Medicare Advantage option at Medicare.gov or at FEHB Open Season?

Through your FEHB enrollment and carrier, not through Medicare.gov. Adding a Medicare Advantage option to an existing eligible FEHB enrollment follows the carrier's rules, and some carriers permit enrollment throughout the year. OPM says you must have Part A and Part B to elect one. Medicare Open Enrollment is for Medicare Advantage plans you buy outside FEHB.

What is the difference between suspending and cancelling FEHB for a Medicare Advantage plan?

Whether you can come back. 5 C.F.R. § 890.304(d)(2) lets an annuitant or survivor annuitant suspend FEHB to enroll in a Medicare Advantage plan (unless a court or administrative order covering a child is in effect and other coverage for the child is not shown), and you can come back: immediately if you lose that plan involuntarily (from 31 days before to 60 days after the loss), otherwise at the next Open Season. Cancel instead and OPM says you "will never be able to reenroll." Both elections go on form RI 79-9, so read which election you are marking.

If I suspended FEHB and leave my Medicare Advantage plan during Medicare's January to March window, does FEHB come back?

Not until the next Open Season. Medicare's Advantage Open Enrollment Period, January 1 to March 31, lets someone already in a Medicare Advantage plan return to Original Medicare. But 5 C.F.R. § 890.306(h)(2) lets an annuitant who suspended FEHB and then left the other coverage voluntarily re-enroll only during the next available Open Season, which means November 2027 for a January 2028 start. Only an involuntary loss of that coverage, which is the qualifying event, reopens FEHB right away.

I'm a Postal annuitant. Does Medicare Open Enrollment satisfy the PSHB Part B requirement?

No. Under 5 U.S.C. § 8903c(e)(1), a Postal Service Medicare covered annuitant who is entitled to Part A (other than through a Part A buy-in) must be enrolled in Part B to enroll in a PSHB plan, unless one of five statutory exceptions applies: a Postal annuitant as of January 1, 2025, who was not both entitled to Part A and enrolled in Part B; a Postal employee at least 64 years old on January 1, 2025; someone living outside the United States for the contract year, with residency shown to USPS; a VA health care enrollee; or someone eligible for Indian Health Service care. Part B enrollment runs through Social Security's own enrollment periods, not Medicare Open Enrollment.

Will I know the 2027 Part B premium before FEHB Open Season ends?

Probably, but not before it starts. As of October 9, 2026, CMS had not announced the 2027 standard Part B premium, and it usually does so in November; the 2027 IRMAA brackets come with the same release. The 2026 figures are $202.90 a month and a $283 deductible. Budget with those, see where your income lands against the 2026 brackets in the IRMAA Cliff Calculator, and re-check before December 14.

When does my Open Season FEHB change take effect as a retiree?

On the first day of the first pay period that begins in January 2027, per the OPM FEHB Handbook's annuitant chapter. Medicare Advantage and Part D elections received by December 7 also start January 1. Check the Handbook's effective date for your annuity before you rely on the two lining up.

Two Windows, Two Jurisdictions

Medicare Open Enrollment belongs to CMS and FEHB Open Season belongs to OPM. The two offices do not share files, and each accepts only its own paperwork.

What you want to do Medicare Open Enrollment (Oct 15 to Dec 7) FEHB/PSHB Open Season (Nov 9 to Dec 14)
Join, drop, or switch a Medicare Advantage plan bought outside FEHB Yes No
Join, drop, or switch a Part D drug plan (if you're in Original Medicare) Yes No
Move between Original Medicare and Medicare Advantage Yes No
Change your FEHB or PSHB plan or option No Yes
Elect a carrier's inside-FEHB Medicare Advantage option (GEHA, for example, under the carrier's enrollment rules) No Yes, with Part A and Part B
Enroll in Medicare Part B No No (Social Security's enrollment periods)
Suspend FEHB for an outside Medicare Advantage plan No (an OPM filing on form RI 79-9; effective date keyed to the other plan's start date if proof arrives within 31 days of it) Filed on RI 79-9 with your retirement system
Cancel FEHB No An OPM filing on RI 79-9; permanent if you leave FEHB for an outside plan (cancelling your own enrollment while continuing as a covered family member has a separate reenrollment rule)

Three things in that table surprise people every year.

First, Medicare Open Enrollment does not enroll anyone in Part B. Part B has its own windows at Social Security. If you skipped Part B at 65, the fall window does not fix that.

Second, the inside-FEHB Medicare Advantage options are FEHB elections. You elect them through your FEHB enrollment and carrier under the carrier's rules (some permit enrollment throughout the year), not on Medicare.gov. OPM's Medicare page is direct: "You must have Part A and Part B to elect a Medicare Advantage plan accessed through FEHB." Some of those options that include drug coverage reimburse part or all of the Part B premium. The amounts are plan-specific, so read each plan's brochure.

Third, suspending or cancelling FEHB is filed with OPM on its own form, RI 79-9, and a suspension's effective date is keyed to the start date of your other coverage when your proof reaches OPM within 31 days before or after that date (otherwise the first day of the first pay period after OPM receives it), not to the Open Season calendar.

The Overlap Month: Decide Medicare by December 7, FEHB by December 14

From November 9 through December 7 both windows are open. That is the stretch in which both routine windows are open, so an outside Medicare Advantage election and an FEHB change can be filed in the same week. A special enrollment period can open a Medicare election at other times.

The order matters because the Medicare deadline comes first and is a receipt deadline. Medicare.gov's enrollment table says coverage starts "January 1 of the next year (the plan must get your request to join by December 7)." A request that reaches the plan after December 7 is late.

Federal Benefits Open Season ends Monday, December 14, 2026, at 11

p.m. Eastern Time. Follow your enrollment system's submission instructions. December 14 falls on a Monday, so the weekend before it is not the last chance to file.

Here is the full calendar for an FEHB or PSHB annuitant with Medicare.

Date Window What it controls
Thursday, October 15, 2026 Medicare Open Enrollment opens Medicare Advantage join, drop, or switch; Part D; Original Medicare to or from Medicare Advantage
Monday, November 9, 2026 FEHB/PSHB Open Season opens Change FEHB or PSHB plan or option, including a carrier's inside-FEHB Medicare Advantage option
November 9 to December 7 Overlap Both an outside Medicare Advantage election and an FEHB change can be filed in the same week
Monday, December 7, 2026 Medicare Open Enrollment closes The outside Medicare Advantage or Part D plan must receive your request
Monday, December 14, 2026, 11
p.m. Eastern Time		 FEHB/PSHB Open Season closes Last routine chance to change FEHB until November 2027
January 1, 2027 Effective dates Medicare Advantage and Part D elections start; annuitant FEHB changes start the first day of the first pay period beginning in January
January 1 to March 31, 2027 Medicare Advantage Open Enrollment Period Leave or switch a Medicare Advantage plan you are already in. Does not reopen a suspended FEHB enrollment
Not yet announced (CMS, usually November) 2027 Part B premium and IRMAA brackets The budget figure for the keep-FEHB-plus-Part-B decision

The One Move You Can't Undo: Cancel vs Suspend

An annuitant who wants to leave FEHB for a private Medicare Advantage plan has two elections to choose from, and they are not the same.

Suspend. 5 C.F.R. § 890.304(d)(2) lets an annuitant or survivor annuitant suspend FEHB to enroll in a Medicare Advantage plan, Medicaid or a similar state program, TRICARE or TRICARE for Life, CHAMPVA, or Peace Corps coverage. Employees cannot suspend; that is an annuitant right. One exception: an enrollee under a court or administrative order covering a child may not suspend or cancel while the order is in effect unless other coverage for the child is shown.

Cancel. OPM's FEHB Handbook, in the annuitant chapter, puts it in one sentence: "When the individual cancels his/her FEHB enrollment as an annuitant, he/she will never be able to reenroll." OPM's Medicare page repeats it: "Canceling FEHB coverage as an annuitant is permanent."

Both elections go on form RI 79-9, Health Benefits Cancellation/Suspension Confirmation. Read which election you are marking.

How a suspension comes back

A suspended enrollment has two routes home, and the difference is whether you chose to leave the other plan.

  • Involuntary loss. If the Medicare Advantage plan terminates, does not renew, or you move out of its service area, 5 C.F.R. § 890.306(h)(1) says you "may immediately reenroll in any available FEHB plan," at any time from 31 days before to 60 days after the loss. No waiting for Open Season.
  • Any other reason. Under 5 C.F.R. § 890.306(h)(2), you may re-enroll only during the next available Open Season. OPM's Medicare page summarizes the pair as re-enrollment "during the annual Federal Benefits Open Season or if you have a QLE."

That second route is the trap behind Medicare's January to March Advantage Open Enrollment Period. That window lets someone already in a Medicare Advantage plan go back to Original Medicare. It does nothing for FEHB. Leave the Medicare Advantage plan on your own in February 2027 and your FEHB does not return until the November 2027 Open Season, for a January 2028 start. Price what keeping your FEHB plan and tier costs in the FEHB Calculator and weigh it against that gap before you file anything.

Timing the suspension so you don't pay a redundant month

The suspension's effective date is keyed to when your documentation reaches the retirement system. Under 5 C.F.R. § 890.304(d)(2), if the proof of your other coverage arrives within 31 days before or after that coverage's effective date, the suspension takes effect the day before that date. Otherwise it takes effect the first day of the first pay period after OPM receives it.

For a Medicare Advantage plan starting January 1, 2027, that means filing RI 79-9 with the enrollment proof between December 1, 2026 and February 1, 2027 so the suspension lands on December 31. File later and you may keep paying the FEHB premium until the suspension takes effect. This rule sets the effective date. A late filing only delays the suspension; it does not forfeit it.

Who else is on your enrollment

A suspension or cancellation ends coverage for everyone on the enrollment. Under 5 C.F.R. § 890.304(d)(3), suspension or cancellation provides no temporary extension of coverage for conversion and no right to convert to an individual contract. A spouse who is not yet on Medicare gets no bridge. The spouse math is worked through in FEHB vs Medicare Advantage at Open Season, which prices the three paths at 2026 rates.

Postal Annuitants: Medicare Open Enrollment Does Not Fix a Missing Part B

PSHB adds a condition FEHB does not have. Under 5 U.S.C. § 8903c(e)(1), a Postal Service Medicare covered annuitant "may not enroll in a Program plan" unless entitled to Part A and enrolled in Part B. Where the annuitant must have Part B, the same condition reaches a family member who is a covered Medicare individual under 5 U.S.C. § 8903c(e)(2), and the exceptions in § 8903c(e)(3) apply as applicable.

The five exceptions in 5 U.S.C. § 8903c(e)(3) are status tests. You either meet one or you do not:

  • A Postal annuitant as of January 1, 2025, who was not both entitled to Part A and enrolled in Part B on that date.
  • A Postal employee who was at least 64 years old on January 1, 2025.
  • Someone who lives outside the United States for the contract year, with residency shown to USPS each year under its rules.
  • Someone enrolled in VA health care under 38 U.S.C. chapter 17, subchapter II.
  • Someone eligible for Indian Health Service care.

None of those are fixed or created in Medicare Open Enrollment. If you need Part B to keep PSHB, that enrollment goes through Social Security's periods, and the PSHB Part B trap post covers the penalty, and the PSHB Part B Calculator prices Part B plus any IRMAA surcharge against your plan's reimbursement. FEHB annuitants have no equivalent requirement; OPM's pages state none.

What Hasn't Been Published Yet

The one number everyone wants before deciding is the 2027 Part B premium. As of October 9, 2026, CMS had not announced it, and the 2027 IRMAA brackets come with the same release. CMS normally announces in November, which can land after Open Season opens but before it closes. The 2026 standard premium is $202.90 a month, with a $283 annual deductible, per medicare.gov's cost page.

Two ways to plan without the number:

  • Your 2027 income-related surcharge (IRMAA), if any, is based on your 2025 tax return. The IRMAA Cliff Calculator shows where an income lands against the 2026 brackets and how close it sits to the next one, the best proxy until CMS publishes 2027's.
  • Read the projection. The 2027 Part B projection tracks the Trustees' estimate and will update when CMS publishes.

If 2025 was a full salary year and you have since retired, the SSA-44 appeal post covers how to get the surcharge recalculated on your lower retirement income.

Compare Your Keep-FEHB Cost Before the Windows Close

Use the free FEHB Calculator to see what your current plan and enrollment tier cost in 2027 next to the alternatives. Pick your plan and tier and the premium side of the decision is done in a minute. Try it now →

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