What if you signed up for Medicare Part A when you turned 65, but didn’t enroll in Part B because you were still working and had health insurance from your employer? Now, at 68 you’re planning to retire this year. What do you need to do to enroll in Medicare Part B, and when do you need to do it?

Kiplinger’s recent article, “What to Know About Enrolling in Medicare Part B,” says that many people who are still working do this. They sign up for Medicare Part A at 65 (because it’s free) and wait to sign up for Part B, while they’re covered by their employer’s insurance. However, you are required to sign up for Medicare Part B no later than eight months after you leave your employment and lose that coverage. Failure to do so, can result in a lifetime penalty and a gap in coverage.

You’re unable to sign up online, since your employer must provide proof that until now you have coverage at work. You must mail in the paperwork by mail or bring it in person to your local Social Security office. You’ll need to complete these forms: CMS-40B Application for Enrollment in Medicare Part B and, because you worked past 65, CMS-L564 Request for Employment Information (to be completed by your employer). If you’ve had more than one job with health coverage since you turned 65, you must also have each employer to fill out a separate form.

The Social Security Administration must then process the paperwork. Mail your application or make an appointment with Social Security at least two months before you retire to ensure that your Part B coverage starts in the first month you’re officially retired. The Social Security office can also provide you with a letter of eligibility or enrollment—that will help with finding a medigap policy, Medicare Part D prescription plan or a Medicare Advantage plan.

Note that only health insurance from a current employer counts as eligible coverage for delaying Medicare sign-up. Therefore, if you have retiree health coverage or if you continue your employer’s coverage through COBRA, you still need to sign up for Medicare Part B within eight months of leaving your job.

Reference: Kiplinger (June 23, 2017) “What to Know About Enrolling in Medicare Part B”