Medicare’s annual open enrollment period begins October 15 and runs through December 7, giving people with Medicare a seven week window to change coverage for 2027. The Centers for Medicare and Medicaid Services said plan costs and benefits can change from year to year, and changes made during open enrollment take effect January 1.
That matters because the federal government has now released its 2027 Medicare Advantage and Part D plan data. CMS said the new plan year will bring shifts in premiums, plan availability and prescription drug coverage, even as the agency says the overall market remains stable.
Federal enrollment window opens as 2027 plan details take effect
CMS said Medicare open enrollment for 2027 coverage runs from October 15, 2026, through December 7, 2026. During that period, beneficiaries can compare Medicare Advantage and prescription drug plans and submit changes that become effective on January 1, 2027.
The agency said people in Medicare health or drug plans should review the materials their plans send each fall, including the Evidence of Coverage and Annual Notice of Change. If a current plan is still offered and still meets a person’s needs, that person generally does not need to re-enroll. But CMS said costs and covered benefits can change from year to year, which is why the annual review matters.
CMS announced September 28 that weighted average monthly Medicare Advantage premiums are projected to fall from $14.37 in 2026 to $12.00 in 2027, a decline of 16.5%. The agency also said the average monthly Part D premium inside Medicare Advantage plans is projected to drop from $11.32 to $7, while the average premium for stand-alone Part D prescription drug plans is projected to rise by less than $1, from $35.09 to $36.
KFF said the average Medicare beneficiary will have 28 Medicare Advantage prescription drug plan options in 2027, down from 32 in 2026. CMS, meanwhile, said more than 99% of Medicare beneficiaries will still have access to at least one Medicare Advantage plan, and 97% will have access to 10 or more options.
What any one senior will face depends on where they live and which plan they have now. CMS published state by state fact sheets showing that premiums, plan counts and access vary widely across the country, even as the national averages point to broad stability.
The agency’s fact sheets repeat the same central warning in every market: plan costs and covered benefits can change from year to year, and beneficiaries should review their options during open enrollment. CMS also said people can compare 2027 coverage options through Medicare’s Plan Finder, which includes premiums, benefits, formularies and other plan details.
National figures do not settle what will happen in every county or ZIP code. In some states, average Medicare Advantage premiums are rising, while in others they are falling. CMS said the fact sheets and landscape files are the best source for local plan counts, premiums and access, and those are the documents beneficiaries will need to check for their own area.
CMS also said people who want to keep their current Medicare coverage generally do not need to re-enroll. But that applies only if the current plan is still being offered and still fits the enrollee’s medical and financial needs for 2027.
One reason for the close attention on 2027 plans is the continuing adjustment in Medicare’s prescription drug market. CMS said in a July 28 fact sheet that it is ending the Part D Premium Stabilization Demonstration at the end of 2026 and returning the program to traditional market conditions in 2027.
CMS said the demonstration had been implemented in 2025 for stand-alone prescription drug plans to address volatility and premium variation following benefit changes required by the Inflation Reduction Act. The agency said plan sponsors now have enough experience under the redesigned Part D benefit to develop 2027 bids without that temporary demonstration.
The broader message for beneficiaries is that change is not always obvious unless they look for it. CMS said that starting in October, Medicare.gov users will be able to review more details about preventive services, connect more easily to plan documents such as formularies and summaries of benefits, and see clear messages about changes affecting their current plans in 2027.
For people who need extra help with costs, CMS said Medicare Savings Programs may help pay premiums and other out of pocket costs, and Extra Help can reduce Part D expenses for qualifying enrollees. The enrollment deadline for 2027 coverage changes remains December 7.