Sign up for Medicare Part B no later than eight months after you leave your job or you could be hit with lifetime penalties. Getty Images By Kimberly Lankford, Contributing Editor June 23, 2017 QI signed up for Medicare Part A when I turned 65, but I didn’t enroll in Part B because I was still working and had health insurance from my employer. But now I’m 68, and I plan to retire later this year. What do I need to do to enroll in Medicare Part B, and when do I need to do it?SEE ALSO: 10 Things You Must Know About Medicare AMany people who are still working just sign up for Medicare Part A at 65 (because it’s free) and delay signing up for Part B while they’re covered by their employer’s insurance. But you must sign up for Medicare Part B no later than eight months after you leave your job and lose that coverage, or else you could get hit with a lifetime penalty and a gap in coverage. You can’t sign up online because your employer needs to provide proof that until now you had coverage at work. You can submit the paperwork by mail or in person at your local Social Security office. You will need to fill out the following forms: CMS-40B Application for Enrollment in Medicare Part B and, because you worked past 65, CMS-L564 Request for Employment Information, to be filled out by your employer. If you’ve had more than one job with health coverage since you turned 65, you’ll need each employer to fill out a separate form. SEE ALSO: How the Medicare Part D Doughnut Hole Works It will probably take the Social Security Administration a while to process the paperwork. Tatiana Fassieux, California Health Advocates board chair, recommends mailing your application or making an appointment with Social Security at least two months before you retire to ensure that your Part B coverage begins the first month you’re officially retired. The Social Security office can also give you a letter of eligibility or enrollment so you can start looking for a medigap policy, and for a Medicare Part D prescription plan or a Medicare Advantage plan, she says. Advertisement Keep in mind that only health insurance from a current employer counts as eligible coverage for delaying Medicare sign-up. If you have retiree health coverage or if you continue your employer’s coverage through COBRA, you’ll still need to sign up for Medicare Part B within eight months of leaving your job, says Medicare advocate Sue Greeno, of the Center for Medicare Advocacy. You can get help with the process from your local State Health Insurance Assistance Program (see the SHIP resource page for links to your state contacts). Also see the Center for Medicare Advocacy’s Eligibility & Enrollment information and the Medicare Rights Center’s Special Enrollment Period fact sheet. SEE ALSO: What You Need to Know About Enrolling in Medicare Got a question? Ask Kim at firstname.lastname@example.org.