My doctor ordered routine blood work, and I got a bill. Doesn’t Medicare cover this?
Medicare covers blood work and other lab tests when a doctor is trying to diagnose or treat a specific illness or injury. But while the program has the authority to cover some preventive care services, such as mammograms and colorectal cancer screenings, original Medicare hasn’t been authorized to pay for routine blood work. That’s why you got the bill. Note that some Medicare Advantage (MA) plans do cover routine blood work as an extra benefit; ask your insurer to find out.

When can I make changes to my Medicare insurance choices?
The primary time is during each year’s open enrollment period, Oct. 15–Dec. 7:

→ If in original Medicare, you can change your Part D prescription drug plan.
→ If in original Medicare, you can switch to a Medicare Advantage (MA) plan.
→ If in an MA plan, you can switch to another MA plan or to original Medicare.

For people in an MA plan, there’s a second open enrollment period: Jan. 1–March 31. During this time, you can switch to a different MA plan or move to original Medicare.

Outside these time windows, you can change a Medicare plan only if you have a “life-changing event”—for example, if you have moved, if your plan is no longer available, or if your financial situation has changed and you now qualify for Medicaid or other financial help.

The story is different for supplemental (or Medigap) policies; they’re not subject to any open enrollment periods, so they can be purchased any time of year. But that’s only if you are able: Insurers in most states can charge you more or deny you coverage if you apply outside your initial open enrollment period.