What if I Want to Wait?
It is possible to forgo Medicare enrollment without being penalized with late enrollment fees. This depends on the number of employees your employer has.
If your employer has at least 20 employees, you don’t need to sign up for Medicare right away. This also applies if you get employer coverage through your spouse. Once you drop the employer coverage, you have eight months to join Medicare Part A and B without penalty, no matter how old you are.
However, if your employer (or spouse’s employer) has fewer than 20 employees - you need to sign up for Medicare as soon as you’re first eligible. This way, you won’t have to worry about any late enrollment penalties.
How Do They Work Together?
When you have Medicare and employer coverage at the same time, the two pay in a distinct order. For example, if you get a treatment that both plans cover, one will pay all that it possibly can first, and then the second insurance plan will cover as much as it can of the remaining portion. The two insurance plans are known as “payers” in this context.
How they work together is known as the coordination of benefits. If the employer has fewer than 20 employees, Medicare pays first. If the employer has 20 or more employees, Medicare pays second.
This works heavily in your favor if you opt to have both Medicare and employer health insurance. When you do this, you can make it so that your treatments can leave you with $0 in out-of-pocket costs (you will, however, still need to make premium payments and deductibles).