Sometimes. If you or your spouse has active employer group health coverage, you may be able to delay Part B without a late enrollment penalty. The rules depend on the type of coverage and the size of the employer. When the employment or employer coverage ends, you generally have an eight-month Special Enrollment Period to enroll in Part B. COBRA and retiree coverage do not always provide the same protections as active employer coverage. If you contribute to a Health Savings Account, ask how enrolling in Medicare could affect your contributions before applying.