Medicare Part D began on January 1, 2006

Medicare Part D is the prescription drug coverage program that became available to all Medicare beneficiaries starting January 1, 2006. It was created by the Medicare Modernization Act, which Congress passed in 2003. Before Part D existed, Medicare covered hospital stays and doctor visits, but not prescription medications — a gap that left many older adults paying full price for drugs or skipping doses to stretch their money.

The program launched as a voluntary benefit, meaning you could choose to enroll or decline it. If you decided not to join when you first became may be able to access and later changed your mind, you would face a permanent penalty on your premiums. That penalty structure remains in place today, which is why understanding the enrollment important date matters even now.

Key Takeaways

  • Medicare Part D started January 1, 2006, filling a gap in prescription drug coverage that had existed since Medicare began in 1965.
  • The program was created by the Medicare Modernization Act of 2003 and launched as a voluntary benefit you could choose to join or decline.
  • If you delayed enrollment without a valid reason, you pay a permanent penalty added to your monthly premium for as long as you have Part D.
  • Private insurance companies run Part D plans under contract with Medicare, so the specific drugs covered and costs vary by plan and by year.
  • The initial enrollment period for Part D is the same as for Medicare itself — the three months before, the month of, and three months after your 65th birthday.

Why Part D was created and what problem it solved

When Medicare launched in 1965, prescription drugs were not a major part of medical treatment the way they are today. By the early 2000s, medications had become central to managing chronic conditions like diabetes, heart disease, and arthritis — but Medicare still did not cover them. Older adults were spending hundreds or thousands of dollars a year on prescriptions, sometimes rationing doses or skipping medications entirely because they could not afford the full cost.

Congress passed the Medicare Modernization Act in December 2003 to address this gap. The law created Part D as a new insurance benefit specifically for prescription drugs. It also created Health Savings Accounts and made other changes to Medicare, but Part D was the centerpiece. The program did not start when ready — there was a two-year gap between the law passing and the benefit launching, which gave insurance companies time to set up plans and gave Medicare beneficiaries time to enroll.

How enrollment worked when Part D launched in 2006

When Part D became available on January 1, 2006, anyone already on Medicare could enroll during an initial open enrollment period that ran from November 15, 2005, through May 15, 2006. People turning 65 after that date had their own enrollment window — the same three-month window before and after their birthday that applies to all Medicare enrollment.

The enrollment process was new and sometimes confusing. Medicare beneficiaries had to choose from multiple private insurance plans offered in their area, each with different drugs covered, different costs, and different pharmacy networks. There was no single "Medicare Part D" — instead, Medicare contracted with private insurers to run the plans. This meant that what was covered and how much you paid depended on which plan you picked and where you lived.

The initial enrollment period was also when the permanent penalty rule took effect. If you were may be able to access for Part D in 2006 and did not enroll, and you later wanted to join, you would pay an extra amount on top of your regular premium for every month you went without coverage. That penalty is still calculated the same way today: 1 percent of the national average Part D premium for each month you were may be able to access but not enrolled.

What Part D covered from the start

Part D coverage was not designed to pay for all prescription drugs. Instead, it worked on a tiered system where you paid different amounts depending on the type of drug and the plan you chose. Most plans had a deductible you paid first, then a copay or coinsurance for each prescription. Once you spent a certain amount out of pocket, you entered what was called the "donut hole" — a gap where you paid the full price of drugs until your total spending reached a catastrophic threshold, at which point Medicare's catastrophic coverage kicked in.

The specific drugs covered varied by plan. Each plan had a formulary — a list of covered medications — and insurers could choose which drugs to include. This meant that a medication your doctor prescribed might be covered by one plan but not another, or might be covered but require you to try a cheaper drug first. This system created real challenges for people who needed specific medications, because switching plans meant potentially losing coverage for the drugs they depended on.

Changes to Part D since 2006

Part D has been modified several times since its launch. In 2011, Congress passed the Affordable Care Act, which gradually closed the donut hole by increasing manufacturer discounts and shifting more of the cost to insurers and the government. By 2020, the donut hole was largely closed for most beneficiaries, though some cost-sharing remained.

In 2023, the Inflation Reduction Act made another major change: it capped the amount Medicare beneficiaries pay out of pocket for Part D drugs at $3,500 per year, and in 2024 that cap dropped to $2,000. It also allowed Medicare to negotiate prices directly with pharmaceutical companies for certain high-cost drugs, something that was not permitted under the original 2003 law.

The enrollment process has also expanded. In addition to the initial enrollment period and the annual open enrollment period (October 15 through December 7 each year), people now have special enrollment periods if they lose coverage, move to a new state, or experience certain life changes. The plans themselves have changed too — some now offer $0 copays for certain drugs, and more plans cover over-the-counter medications.

How Part D enrollment works today

If you are turning 65 now, you have the same enrollment window that existed in 2006: the three months before your birthday, the month of your birthday, and three months after. If you miss that window and do not have other creditable coverage, you can still enroll during the annual open enrollment period from October 15 through December 7, but you will pay the permanent late penalty.

You still choose from multiple plans offered by private insurers in your area. Medicare publishes a plan finder tool on Medicare.gov where you can enter your medications and see which plans cover them and what your costs would be. The plans change every year — the drugs covered, the copays, the deductibles, and even which insurers offer plans in your area can all shift. This is why it is important to review your coverage every fall, even if you have been on the same plan for years.

The penalty for late enrollment is still 1 percent of the national average Part D premium per month of delay, and it is permanent. If you go without Part D coverage for 63 months (more than five years), the penalty is calculated on 63 months of premiums, and you will pay that extra amount for the rest of your life on Medicare. There are narrow exceptions — if you had other creditable coverage, such as from an employer or union, you do not owe a penalty — but you have to prove it.

Frequently Asked Questions

Can I enroll in Part D anytime, or only during certain periods?

You can enroll during your initial enrollment period (the three months before, the month of, and three months after you turn 65), during the annual open enrollment period (October 15 through December 7), or during a special enrollment period if you lose coverage or move. If you miss all of these and do not have creditable coverage, you can still enroll, but you will owe a permanent penalty.

What happens if I do not enroll in Part D when I first become may be able to access?

If you do not enroll and do not have other creditable drug coverage, you will owe a permanent penalty added to your monthly premium. The penalty is 1 percent of the national average Part D premium for each month you were may be able to access but not enrolled. This penalty stays with you for life, even if you switch plans or move to a different state.

Does Part D cover all prescription drugs?

No. Each plan has a formulary — a list of covered drugs — and insurers decide which medications to include. Your doctor's prescription might be covered by one plan but not another. You can use the Medicare plan finder to check whether your specific medications are covered before you enroll in a plan.

Can I switch Part D plans if I do not like mine?

Yes. You can switch plans during the annual open enrollment period (October 15 through December 7), and the new coverage starts January 1. You can also switch if you experience a may have access to life event, such as losing other coverage or moving to a new state. Some plans also allow you to switch once per year outside the open enrollment period.

How much does Part D cost?

Part D costs vary by plan and by year. Each plan has its own monthly premium, deductible, and copays or coinsurance amounts. In 2024, premiums range widely depending on which plan you choose and where you live. You can see the exact costs for plans in your area using the Medicare plan finder on Medicare.gov.