When you get health care services, 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. These include the "Medicare Summary Notice" (MSN) if you have Original Medicare, or similar statements that list the services you got or prescriptions you filled.
If you find items listed in your claims that you don’t have a record of, it’s possible that you or Medicare may have been billed for services or items you didn’t get. If you think a charge is incorrect and you know the provider, you may want to call their office to ask about it. 
The person you speak to may help you better understand the services or supplies you got. Or, your provider may realize a billing error was made.
If you've contacted the provider and you suspect that Medicare is being charged for a service or supply you didn't get, or you don't know the provider on the claim, you can:
n Call 800-MEDICARE
n Report it online to the Office of the Inspector General.Call the Office of the Inspector General at 800‑HHS‑TIPS (800‑447‑8477). TTY users should call 800‑377‑4950
Have this information before you report fraud:
n The provider's name and any identifying number you may have
n The service or item you're questioning
n The date the service or item was supposedly given or delivered
n The payment amount approved and paid by Medicare
n The date on your MSN
n Your name and Medicare number
n The reason you think Medicare shouldn't have paid
n Any other information you have showing why Medicare shouldn't have paid for a service or item
Fighting fraud can pay up to $1,000. You may be eligible for a reward if:
n The allegation must be specific, not general.
n The suspected Medicare fraud you report must be confirmed as potential fraud by the Program Safeguard Contractor, the Zone Program Integrity Contractor, or the Medicare Drug Integrity Contractor (the Medicare contractors responsible for investigating potential fraud and abuse). 
The frarud must be formally referred as part of a case by one of the contractors to the Inspector General for further investigation.
n You aren't an "excluded individual, which simply means that you didn't participate in the fraud offense being reported. Or, there isn't another reward that you qualify for under another government program.
n The person or organization you're reporting isn't already under investigation by law enforcement.
n Your report leads directly to the recovery of at least $100 of Medicare money.
The incentive reward can't exceed 10 percent  of the overpayments recovered in the case or $1,000, whichever is less. 
If multiple individuals qualify for a reward, the reward is shared among them. 
If you want to know more about the Incentive Reward Program, call 800-MEDICARE.