Medicare Enrollment Guide: When and How to Sign Up

1. Medicare Parts Explained

Medicare is divided into four parts, each covering different types of care:

• Part A (Hospital Insurance): Covers inpatient hospital stays, skilled nursing facility care, hospice, and some home health care. Most people get Part A premium-free if they or a spouse paid Medicare taxes for at least 10 years.
• Part B (Medical Insurance): Covers outpatient care, doctor visits, preventive services, durable medical equipment, and some home health services. Part B requires a monthly premium that is income-adjusted.
• Part C (Medicare Advantage): Private insurance plans that bundle Parts A and B and often include drug coverage and extras like dental and vision. You must have Parts A and B to enroll in Part C.
• Part D (Prescription Drug Coverage): Covers prescription medications through private insurance plans. Available as a standalone plan or bundled within a Medicare Advantage plan.

Original Medicare (Parts A and B) does not cover everything. Most beneficiaries also enroll in a Medigap supplemental policy or a Medicare Advantage plan to fill coverage gaps.

2. Enrollment Periods

Medicare has strict enrollment windows. Missing them can result in coverage gaps and permanent premium surcharges.

• Initial Enrollment Period (IEP): A seven-month window around your 65th birthday (three months before, your birthday month, and three months after). This is the best time to sign up for Parts A and B with no penalty.
• General Enrollment Period (GEP): January 1 through March 31 each year. Coverage starts July 1. A late-enrollment penalty may apply if you missed your IEP without qualifying for a Special Enrollment Period.
• Open Enrollment Period: October 15 through December 7. During this window, you can switch between Original Medicare and Medicare Advantage, change Advantage plans, or join or drop a Part D drug plan.
• Special Enrollment Period (SEP): Available if you delayed enrollment because you had creditable coverage through an employer or union. No penalty applies if you enroll within eight months of losing that coverage.

3. Late-Enrollment Penalties

Delaying enrollment without creditable employer coverage triggers permanent premium increases:

• Part B penalty: Your monthly premium increases by 10% for each full 12-month period you were eligible but not enrolled. This surcharge lasts for as long as you have Part B.
• Part D penalty: Calculated as 1% of the national base beneficiary premium multiplied by the number of months you went without creditable drug coverage. Like the Part B penalty, it is permanent.

These penalties compound over time, so enrolling on schedule is one of the most financially significant decisions in retirement planning.

4. Forms You May Need

Depending on your situation, you may need to file one or more of these forms with Medicare:

• CMS-40B (Application for Enrollment in Medicare Part B): Use this if you delayed Part B because you had employer coverage and now want to enroll during a Special Enrollment Period.
• CMS-L564 (Request for Employment Information): Your employer or former employer completes this form to verify that you had group health coverage. It must be submitted with CMS-40B.
• SSA-1 (Application for Retirement/Medicare): If you are also applying for Social Security retirement benefits, this single form enrolls you in both.

BeneFill can auto-fill your personal details, employment dates, and employer information on CMS-40B and CMS-L564, reducing errors on these time-sensitive forms.

5. Special Enrollment Period

The Special Enrollment Period (SEP) protects people who delay Medicare Part B because they have group health plan coverage through current employment. The SEP begins the month employer coverage ends (or the month employment ends, whichever comes first) and lasts eight months. During this window, you can enroll in Part B without a late penalty.

Important: COBRA and retiree health coverage do not count as coverage based on current employment. If you rely on COBRA after leaving your job, your SEP clock starts when your active employment ends, not when COBRA expires. This catches many people off guard and is one of the most common Medicare enrollment mistakes.

6. Tips for a Smooth Enrollment

• Mark your IEP dates on your calendar well in advance. Your seven-month window starts three months before the month you turn 65.
• If you have employer coverage, get a letter from your HR department confirming your coverage dates before you retire.
• Have your employer fill out CMS-L564 before your last day of work; getting the form completed after you leave can be surprisingly difficult.
• Compare Medigap and Medicare Advantage plans during your initial Medigap open enrollment period (six months starting when Part B begins), since this is the only time Medigap insurers must accept you without medical underwriting.
• Review your Part D drug plan annually during Open Enrollment; plan formularies and premiums change every year.