The Centers for Medicare & Medicaid Services will publish the complete slate of 2027 Medicare Advantage and Part D plan prices in mid-to-late September, the agency confirmed in a July 28 bid announcement, giving tens of millions of Medicare beneficiaries their first real look at next year’s premiums, deductibles and drug costs before the annual shopping window opens. The release comes after CMS quietly finalized the government-side inputs that steer those prices, well ahead of the plan-mailed notices insurers must send by month’s end. For a market where switching or staying with the wrong plan can swing a retiree’s costs by hundreds of dollars over a year, that runway before Open Enrollment is the entire ballgame.
CMS Locks In the Building Blocks Before Insurers Finalize a Single Plan
CMS released preliminary technical Part D bid information for contract year 2027 on July 28, along with the national average monthly bid amount, the base beneficiary premium, Part D regional low-income subsidy amounts, Medicare Advantage regional benchmarks and the income-related monthly adjustment amounts that determine what higher earners pay. Those figures are the scaffolding insurers use to finalize what they will actually charge enrollees — they are not the plan-level premiums or deductibles a beneficiary will see on an enrollment card. The base beneficiary premium is capped so it cannot rise more than 6% year over year through 2029 under the Inflation Reduction Act’s premium-stabilization formula, a guardrail written into law because standalone drug-plan premiums swung sharply in earlier years of the redesigned benefit.
The same July 28 release also announced the end of the Part D Premium Stabilization Demonstration, a program CMS ran since 2025 to smooth out volatility in standalone prescription drug plan premiums after the Inflation Reduction Act rewrote the Part D benefit. CMS said its own bid analysis found that plan sponsors now have enough experience under the redesigned benefit to price coverage without the extra backstop, so the demonstration ends at the close of contract year 2026 and Part D returns to ordinary market conditions for 2027 — a shift that could show up as wider premium swings between standalone drug plans than shoppers saw the past two years, even though the aggregate figures CMS just published look stable.
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What Actually Lands in the September Landscape File
The document beneficiaries and agents actually wait for is the Medicare Advantage and Part D landscape file, which CMS has said it will release, as in past years, in mid-to-late September once every insurer’s offerings are finalized. That file — not the July bid data — is what carries the real plan-by-plan numbers: premiums, deductibles, star ratings and formulary details for the specific Advantage and drug plans sold in a given county. CMS has said it will publish final average Medicare Advantage and Part D premiums alongside the landscape release rather than before it, meaning any premium figure circulating before that date is, by definition, an estimate rather than the finished product.
Plan-level detail typically becomes visible on Medicare’s own plan-comparison tool around October 1, roughly two weeks before Open Enrollment begins. Insurers are separately required to mail Annual Notices of Change spelling out how a member’s current plan is changing for 2027 no later than September 30, though many carriers send them in late August or early September — well before CMS’s own landscape file is public. That gap means a retiree can receive a notice describing next year’s version of their current plan before the tool that lets them compare it against every competing plan in their county is actually live.
That sequencing has tripped up shoppers in past enrollment cycles: a beneficiary who reads an ANOC in late August and decides to stick with their current plan, or to switch based on an early marketing call, is making that decision without the one document — the landscape file — that lays out every alternative side by side. Counselors typically tell callers to hold major decisions until the landscape file and Medicare’s Plan Finder tool both reflect the same September data set, rather than acting on an ANOC or a sales pitch in isolation.
The Narrow Window Before Open Enrollment Opens Oct. 15
Medicare’s Annual Enrollment Period runs October 15 through December 7, the same window every year, and it is the only stretch when most beneficiaries can freely switch Medicare Advantage plans, switch Part D drug plans, or move between Advantage and Original Medicare for coverage that starts January 1. The mid-to-late-September landscape release is timed to land inside a runway of roughly two to four weeks before that window opens — long enough, in theory, for a beneficiary to pull their current plan’s 2027 numbers, run their prescriptions through Medicare’s Plan Finder, and compare that against every other plan sold in their ZIP code before they have to act.
The stakes are highest for people whose circumstances changed in the past year — a new diagnosis, a new prescription, a move to a different county, or income that crossed an income-related threshold and now carries a monthly surcharge added directly to Part B and Part D premiums. Beneficiaries weighing a switch into or out of a Dual-Eligible Special Needs Plan face the same sequencing problem: those plans’ 2027 benefit packages are folded into the same landscape release, so a decision to switch cannot be fully informed until the same September data set is public.
Medicare’s Plan Finder tool lets a beneficiary enter every current prescription and preferred pharmacy once the September data set loads, then rank Advantage and Part D plans in a county by projected annual cost rather than by advertised premium alone — a distinction that matters because a plan with a low sticker premium can still carry a higher total cost once deductibles, tiered drug pricing and out-of-pocket maximums are factored in. That full ranking is unavailable until the landscape file publishes, which is why licensed agents and State Health Insurance Assistance Program counselors routinely tell beneficiaries not to lock in a decision based on August or early-September marketing alone.
The bigger unresolved question is what happens to standalone Part D premiums now that the demonstration meant to stabilize them has ended. CMS frames the shutdown as a sign the market has matured under the rewritten drug benefit, not as a warning — but the agency built that stabilization program in the first place because premiums swung sharply when Part D was redesigned under the Inflation Reduction Act, and the September landscape file will be the first real test of whether standalone drug plans behave differently without it.
This article was produced with the assistance of AI and reviewed by The Money Overview editorial team before publication.
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