ACCORDING TO THE Coalition Against Insurance Fraud, scams against government and private health care insurers form the largest type of insurance fraud – by far. No one knows exactly how much money is lost through health care fraud, but it is likely in the tens of billions of dollars a year, the group claims. In addition, medical identity theft is now one of the top complaints received by the Federal Trade Commission, CNBC reports.

Government insurance, including Medicare, is a frequent target. Indeed, scammers are using this year's newly issued Medicare ID cards as a way to steal identities. The new cards replace Social Security numbers with randomly generated, 11-character numbers. Scammers posing as Medicare officials are asking people to pay for the new cards, which are in fact free. Or they are calling people to say they have a refund coming and need the ID number and a bank account number to deposit it. These, and many other Medicare scams, are used to steal money or the person's identity and use it for their own medical care or sell it on the black market.

Billing fraud is another huge problem, and it's not always easy to tell what is legitimate and what isn't. "There can be confusion about services that are being billed for, and it is hard to parse out if it's fraud or a billing error," says Fred Riccardi, vice president of client services at the Medicare Rights Center. Fortunately, there are many resources to help.

Fraud Prevention Tips

The Centers for Medicare and Medicaid Services lists numerous tips for preventing fraud on its website. Some of the most critical include:

• Protect your Medicare and Social Security numbers and treat your Medicare card like it's a credit card. Don't give your Medicare card or number to anyone except your doctor or people you know should have it.
• Remember that nothing is ever "free." Don't accept offers of money or gifts for free medical care.
• Educate yourself about Medicare. Know your rights and what a provider can and can't bill to Medicare.
• Be wary of providers who tell you that the item or service isn't usually covered, but they "know how to bill Medicare" so Medicare will pay.
• Always check your pills before you leave the pharmacy to be sure you got the correct medication, including whether it's a brand-name or generic and the full amount. If you don't get your full prescription, report the problem to the pharmacist.

There are just as many don't's as do's. The most important: Don't believe everything you hear from unknown sources. During open enrollment and throughout the year, "you will be inundated from many forms of communication," says Chris Hakim, vice president of Medicare products for eHealth, an online marketplace for health insurance plans. "Consumers need to be very wary and look for reputable organizations."

Medicare will never call you on the phone and ask for information, and selling Medicare products and services door to door is prohibited by law, Hakim says. CMS warns against being taken in by media advertising as well because many television and radio ads "don't have your best interest at heart," it explains.

Robocalls are a big problem. "I get four or five a day," says Tatiana Fassieux, a consultant with California Health Advocates, a Medicare advocacy organization. "Don't succumb to those free back and knee brace offers. You may not get what you really need because your doctor is not involved, and also it is an open door to having whoever is doing this to continue submitting claims that the individual hasn't gotten or needed."

Also, beware of marketing approaches by insurance plans and agents. "No door-to-door solicitation is allowed for Medicare plans," Fassieux says. And don't believe it when an agent or broker claims he can get you a better deal. "All rates are fixed and filed with the government," Hakim says. "Whether it's an agent or a carrier, you cannot get a better rate with someone over another."

Review Your Statements

Whenever you use your benefits, be sure to carefully review your Medicare claims for errors. "We always say, read your Medicare Summary Notice and explanation of benefits, and try to eliminate the possibility that there was an error," Riccardi says. CMS recommends you record the dates on a calendar and save the receipts and statements you get from providers to check for mistakes. Compare the dates and services on your calendar with the statements you get from Medicare to make sure you got each service listed and that all the details are correct. If you think a charge is incorrect and you know the provider, call their office and inquire about it. The office may be able to explain the confusion or may realize it made a billing error. Check claims early, because the sooner you see and report errors, the sooner they can be corrected or stopped.

Remember, there are organizations out there to help. The Senior Medicare Patrol is an online resource dedicated to fighting Medicare fraud and abuse. There are both national and state programs to educate consumers about fraud, Riccardi says. "We just helped a beneficiary who did not receive new Medicare card. We called Medicare and verified her information, and they are sending her a new card. That was a voluntary action of the beneficiary, versus getting a phone call where some entity was trying to get her information," he says.

If you suspect fraud of any kind, report it right away:

• Call CMS at 1-800-MEDICARE (1-800-633-4227).
• Report it online to the Department of Health and Human Services Office of the Inspector General.
• Call the Office of the Inspector General at 1‑800‑HHS‑TIPS (1‑800‑447‑8477) or TTY: 1‑800‑377‑4950.
• Call your state insurance department or law enforcement.