Sometimes Medicare will decide that a particular treatment or service isn’t covered, and will deny your claim. The good news is that if you believe you should have been paid, you can appeal.

The federal government makes the general rules for Medicare, but the day-to-day administration is handled by private insurance companies that contract with the government. In addition, the government contracts with committees of physicians who decide the appropriateness of care received by most Medicare beneficiaries in hospitals.

Many of the decisions made by insurance companies and doctors’ committees are highly subjective. For instance, they might involve a judgment call as to whether a given treatment is medically necessary, or whether a service is “custodial care” as opposed to medical care.

If Medicare refuses to pay for a treatment or service, you’ll learn this when you receive your “Medicare Summary Notice” in the mail.

A good first step is to find out whether the denial of coverage is simply the result of a coding mistake. You can ask your doctor to confirm that the correct medical code was used on the Medicare paperwork. If it wasn’t, that might solve the problem right there.

If the code was correct and you still believe Medicare should have paid, you can appeal the decision through Medicare’s internal review process.

If that doesn’t work, you can go to court. This is allowed as long as the amount in dispute is at least $1,000 (or $2,000 for some types of claims). An attorney can represent you in the case.

According to the Medicare Rights Center, only about 2 percent of Medicare beneficiaries appeal denials of care. But 80 percent of those who appeal Part A denials – and 92 percent of those who appeal Part B denials – win more care as a result.

Even if Medicare was correct in denying coverage, beneficiaries can sometimes avoid having to pay for a treatment if they can show that they didn’t know and couldn’t have been expected to know that a particular treatment wouldn’t be covered.