Medicare Open Enrollment 2026: Dates and What to Check
Every Medicare enrollment window for 2027 coverage, with dates, who can use each one, and what to check before the December 7 deadline.
Medicare open enrollment for 2027 coverage runs from October 15, 2026 to December 7, 2026. Changes you make take effect on January 1, 2027. If you are already in a Medicare Advantage plan, a second window, the Medicare Advantage Open Enrollment Period, runs from January 1, 2027 to March 31, 2027 and allows one switch.
Official Every figure on this page is published by the responsible agency; none is a projection.
| Period | When | Coverage starts |
|---|---|---|
| Annual Enrollment Period (open enrollment)Anyone with Medicare: switch between Original Medicare and Medicare Advantage, change Advantage plans, join, switch or drop a Part D drug plan. (42 CFR §422.62 (MA election periods)) | October 15 – December 7, 2026 | January 1, 2027 |
| Medicare Advantage Open Enrollment PeriodOnly if you are already in a Medicare Advantage plan: one switch to another Advantage plan, or back to Original Medicare (and join a separate drug plan). (Medicare.gov, Joining a plan) | January 1 – March 31, 2027 | First of the month after the plan gets your request |
| Initial Enrollment PeriodYour first chance to sign up for Part A and Part B. (42 CFR §407.14 (initial enrollment period)) | Seven months: 3 before the month you turn 65, that month, 3 after | Depends on the month you sign up |
| General Enrollment PeriodSign up for Part A or Part B if you missed your Initial Enrollment Period. Late-enrollment penalties can apply. (42 CFR §407.15 (general enrollment period)) | January 1 – March 31, 2027 | First of the month after you sign up |
| Special Enrollment PeriodsFor example, signing up for Part B later without a penalty because you or your spouse had job-based coverage from current work, or changing plans after a move out of your plan’s service area. (42 CFR §407.20 (special enrollment period for group health plan coverage)) | Triggered by events | Varies |
What to check before December 7
- Your plan’s Annual Notice of Change. Your plan sends it before open enrollment. Premiums, drug lists and pharmacy networks can change every January.
- Part D in 2027. The standard deductible and the out-of-pocket cap both rise in 2027. See the 2027 Part D figures →
- The Part B premium for 2027. CMS announces it in the autumn, usually in November. 2027 Part B premium →
- Deductibles for 2027. Part A and Part B deductibles are set with the premium. 2027 deductibles →
- Your IRMAA bracket. 2027 surcharges are set by your 2025 tax return. 2027 IRMAA brackets (projected) →
Late-enrollment penalties
Part B: 10% of the standard premium for each full 12 months you could have had Part B but did not, added for as long as you have Part B (42 U.S.C. §1395r(b) (Part B late-enrollment increase)). On the 2026 standard premium of $202.90, one year late adds $20.29 a month.
Part D: 1% of the national base beneficiary premium for each full month without Part D or other creditable drug coverage after your Initial Enrollment Period, rounded to the nearest $0.10, for as long as you have Part D (42 U.S.C. §1395w-113(b) (Part D late-enrollment penalty), 42 CFR §423.286(d)(3) (penalty amount, rounded to the nearest $0.10)). With the 2027 base premium of $41.33, 12 months without coverage adds $5.00 a month in 2027. Late-enrollment penalty calculator →
When is your Initial Enrollment Period?
Medicare treats you as 65 on the day before your 65th birthday, so a birthday on the 1st puts you in the previous month.
Your 2027 Medicare premium was set by your 2025 income. QuantCalc runs your whole retirement — Social Security, withdrawals, taxes, Medicare surcharges — year by year.
Run the free tax-aware simulation →Common questions
When is Medicare open enrollment in 2026?
Medicare open enrollment for 2027 coverage runs from October 15, 2026 to December 7, 2026. Changes you make take effect on January 1, 2027. If you are already in a Medicare Advantage plan, a second window, the Medicare Advantage Open Enrollment Period, runs from January 1, 2027 to March 31, 2027 and allows one switch. Sources: 42 CFR §422.62 (MA election periods) and Medicare.gov, Joining a plan.
What can I change during open enrollment?
You can switch from Original Medicare to a Medicare Advantage plan or back, change Advantage plans, and join, switch or drop a Part D drug plan (Medicare.gov, Joining a plan). The plan must receive your request by December 7, 2026.
What if I miss December 7?
If you are in a Medicare Advantage plan you get one more switch from January 1, 2027 to March 31, 2027. If you are in Original Medicare, most changes wait for the next Annual Enrollment Period unless a Special Enrollment Period applies (Medicare.gov, Joining a plan).
How much is the Medicare late-enrollment penalty?
Part B adds 10% of the standard premium per full year of delay (42 U.S.C. §1395r(b) (Part B late-enrollment increase)); Part D adds 1% of the national base beneficiary premium per uncovered month, $41.33 in 2027 (42 U.S.C. §1395w-113(b) (Part D late-enrollment penalty)). Both last as long as you have the coverage.
Sources
- 42 CFR §422.62 (MA election periods)
- 42 CFR §423.38 (Part D enrollment periods)
- 42 CFR §407.14 (initial enrollment period)
- 42 CFR §407.15 (general enrollment period)
- 42 CFR §407.20 (special enrollment period for group health plan coverage)
- Medicare.gov, Joining a plan
- 42 U.S.C. §1395r(b) (Part B late-enrollment increase)
- 42 U.S.C. §1395w-113(b) (Part D late-enrollment penalty)
- 42 CFR §423.286(d)(3) (penalty amount, rounded to the nearest $0.10)
Every figure on this page is read at build time from one dataset and was checked against the text of the documents above on September 24, 2026. Every figure with its source: JSON. QuantCalc is calculation software, not tax, legal or benefits advice.
Related
2027 Part B premium → 2027 IRMAA brackets (projected) → Late-enrollment penalty calculator → 2026 IRMAA brackets →