Now it’s getting personal. I just got a notice from HHS that I’m going to be automatically enrolled in Medicare Part A as of the first day of November, four months from now. I’m also going to be enrolled in Medicare Part B on that date unless I opt out of it.

Okay, what’s covered here?
Medicare Part A:

• Hospital care
• Skilled nursing facility care
• Nursing home care (as long as custodial care isn’t the only care you need)
• Hospice
• Home health services

And Part B? Part B is the day-to-day stuff. It covers medically necessary services, services or supplies that are needed to diagnose or treat your medical condition and that meet accepted standards of medical practice, and preventive services, health care to prevent illness (like the flu) or detect it at an early stage, when treatment is most likely to work best.

You pay nothing for most preventive services if you get the services from a health care provider who accepts assignment.

Part B covers things like:

• Clinical research
• Ambulance services
• Durable medical equipment (DME)
• Mental health
• Inpatient
• Outpatient
• Partial hospitalization
• Getting a second opinion before surgery
• Limited outpatient prescription drugs

Well, that sounds good. So why would you opt out, particularly if there’s a penalty assessed if you don’t enroll?

You’d opt out if you’re already covered by a spouse’s insurance and that insurance gets billed for your care before Medicare does. In that circumstance there’s no penalty.

Otherwise, enroll.

Regardless of whether you have Medicare based on disability or age, you should definitely enroll in Part B (or not refuse it) if you have health insurance that will automatically become secondary to Medicare (it will pay after Medicare does) when your Medicare benefits begin. This includes the following:

• Health insurance that you buy yourself on the open insurance market and that isn’t provided by an employer
• Health insurance from an employer with fewer than 20 employees (if you’re 65 or older)
• Health insurance from an employer with fewer than 100 employees (if you have Medicare due to disability)
• Retiree benefits from a former employer (your own or your spouse’s)
• Health benefits from the military’s TRICARE For Life retiree program

You should enroll in Part B coverage in the preceding situations for a very good reason quite apart from the possibilities of late penalties down the road if you don’t. When Medicare is considered primary coverage, it pays your medical bills first.

So if you’re not enrolled in Part B, you run the real risk of having your insurance plan deny any claims that Medicare could’ve paid — from basic ones like doctors’ visits and lab tests to major ones like surgery. In other words, you may face having to pay the entire bill.

The premium isn’t insignificant: for most people it’s $104.90 per month, which can be roughly 10% of your Social Security income. But think of the alternative. Who can afford to pay medical bills out of pocket?