You’re filling out a pile of forms at the local hospital or when seeing a physician. You jot down your name, address, and insurance information. Then you come to a space for your Social Security number. Should you fill in those precious nine digits? If it’s your doctor or hospital asking, the answer is “No!” But it’s not so simple if you have Medicare or the question comes from your health insurance company. Here’s what you need to know.

Health care providers: Just say no

Doctors, hospitals, and other health care providers may want your Social Security number to help with debt collection in the case of a problem with your insurance company or an unpaid copay. But you’re under no obligation to hand over that information.

“There’s really no reason to give your doctor or hospital your Social Security number,” says Consumer Reports medical adviser Orly Avitzur, M.B.A., M.D., whose office stopped asking patients for their numbers about three years ago. “Insurers have your unique subscriber number and that’s what we use to submit claims.”

And there’s good reason to keep your Social Security number away from health care providers, says Paul Stephens, director of policy and advocacy at the nonprofit Privacy Rights Clearinghouse in San Diego. Giving up your Social Security number, which Stephens likens to the “keys to the kingdom,” can easily compromise your privacy and security if your medical records are stolen, as in the case of the recent hack of the health insurance companies of Anthem, Inc. “Both small and large providers may not have adequate security protocols to protect it,” he says. “And in the medical area you have a double whammy—medically sensitive and financially sensitive information.”

CR’s advice: If a health care provider asks for your Social Security number:

Leave the area on the form blank. Often, the provider won't even ask or notice.

If they do, consider what Stephens often says: “I explain that I’m concerned about identity theft and prefer not to reveal my Social, except in those situations where it’s mandated by law.” If you feel pressured, consider choosing another facility or doctor, if you can. Some folks offer just the last four digits of their number.

Read the "Paranoid Guide to Digitial Security" and our guide to Internet security. And find out whether you should get a new Social Security number.

Medicare patients: Guard your ID card

People on Medicare, however, have no choice but to share their Social Security numbers with doctors and hospitals. That’s because your Medicare ID is your Social Security number (followed by a code)—it’s right on your Medicare card for the world to see. There have been attempts over the past few years to remove Social Security numbers from Medicare cards; a new bill, the Medicare Identity Theft Prevention Act of 2015, was introduced just weeks ago.

CR’s advice: If you're on Medicare, you still have to share your Social Security number with your health care providers (in the form of your Medicare card), so they can get paid by Medicare. But you can get some protection by making a copy of your original card and, after the first visit, blacking out all but the last four digits of your Social Security number. That way you won’t have to carry around your original card, with your complete Social Security number, at all times.

Insurance companies: You’re out of luck

Insurance companies do have a right to ask for your Social Security number, whether you get insurance through your employer or you bought an Obamacare plan through a state or federal marketplace.

Federal law—in the form of the Mandatory Insurer Reporting law—instructs group plan issuers to report Social Security numbers to the Centers for Medicare and Medicaid Services for subscribers and covered dependents. The ostensible reason: to cut down on payment errors and possible fraud.

The Affordable Care Act also provides no relief on this front. People who apply for insurance under the ACA are asked to provide Social Security numbers for everyone in their household—particularly adult, tax-filing family members whose earnings can be used to check your household’s eligibility for an insurance subsidy. The only exceptions: legal immigrants who don’t have a Social Security number. (The ACA has other requirements for them).

CR’s advice: If you get insurance through your employer, you could ask if you really need to provide the information. “We’ve heard anecdotally that if customers refuse, there may be no consequences,” Stephens says. But if you’re applying for a marketplace plan, refusing to provide the information may interfere with signup.

—Diane Umansky





More from Consumer Reports:

It’s time to buy a new phone, here’s why

Dos and don’ts of itemized tax deductions

Top 5 ways to boost the value of your home





Consumer Reports has no relationship with any advertisers on this website. Copyright © 2006-2015 Consumers Union of U.S.