Protecting your Social Security number is one of the main ways to protect yourself from identity theft.

But sometimes people are asked to provide their Social Security number. When is it safe to do? When should someone not provide that information?

Security experts say that there are four common situations where you should avoid giving out your Social Security number.

“If someone calls you, they already know who you are,” says consumer advocate Adam Levin.

Levin says that you should avoid providing your Social Security number to anyone who contacts you.

“If someone contacts you representing themselves as being with the government, or a financial institution or health care provider, and they ask you to authenticate yourself, hang up,” he says.

Doctors may ask for your information, but experts say that they will usually settle for insurance information instead.

You should never give your number to a business, unless you are applying for credit.

You also should never have to provide a Social Security number to sign a child up for sports, camp or any other program.

But even if you are not required to provide a Social Security number, the law may not require the business to serve you without one. So what should you do?

You can try to leave the space blank. But if that doesn’t work, ask questions – Am I required to provide this? What will you use it for? What happens if I decline? Will you accept another form of identification?

There are some times when providing your Social Security number will be required, such as applying for a driver’s license, opening a bank account or dealing with a government agency like the IRS.