Visit the Source: https://www.medicareinteractive.org/get-answers/coordinating-medicare-with-other-types-of-insurance/job-based-insurance-and-medicare/job-based-insurance-when-you-are-disabled
Job-based insurance when you are disabled - Job-based insurance and Medicare Part 2
Job-based insurance is insurance offered by an employer or union for current employees and family members. job-based insurance allows you to delay Medicare enrollment. However, yo may want to enroll in Medicare depending on whether your job-based insurance pays Primary or Secondary. In most cases, you should only delay Part B if your job-based insurance is the primary payer (meaning it pays first for your medical bills) and Medicare is secondary.
If you are eligible for Medicare due to a disability (meaning you are collecting Social Security Disability Insurance) and are covered by your, your spouse's, or in some cases a family member's job-based insurance, you have a Special Enrollment Period (SEP) to enroll in Part B up to eight months after you no longer have coverage from current work. This means that you are not required to enroll in Part B when you first become eligible for Medicare (but you MUST have Part A to keep SSDI). However, remember that i most cases you should only delay Part B enrollment if our job-based insurance is the PRIMARY payer.
-- Job-based insurance is primary if it is from an employer with 100+ employee. Medicare is secondary in this case, and some people choose not to enroll in Part B because of the additional monthly premium.
-- Job-based insurance is secondary if it is from and employee with fewer than 100 employees. Medicare is primary in this case, and if you delay Medicare enrollment, your job-based insurance may provide little or no coverage. You should enroll in Part B to avoid incurring high costs for your care. >> If you have job-based insurance from a family member and Medicare is primary, you do not have a Part B SEP. You should enroll in Medicare as soon as you are eligible to avoid penalties and gaps in coverage. << -- NOTE: THERE ARE DIFFERENT RULES IF YOU ARE MEDICARE-ELIGIBLE DUE TO AGE OR BECAUSE YOU HAVE ESRD.
To find out if your job-based insurance is primary or secondary, contact your or your spouse's human resources department. If you plan to delay enrollment into Part B and use the SEP later, keep records of our health insurance coverage. you will be required to submit proof of our enrollment in job-based insurance when using the SEP to enroll in Part B. Proof of enrollment in job-based insurance includes: -- Written notice from your employer or plan -- Documents that show health insurance premiums paid, including W-2s, pay stubs, tax returns, and/or receipts -- Health insurance cards with the appropriate effective date
NOTE: If you have another form of insurance from your employer, like COBRA or retiree insurance, there are different rules for how Medicare works with your plan.