When it comes to protecting your Social Security number, there is a crucial step you should take: Sign up for an online account with the Social Security Administration.

The agency no longer mails statements to individuals who are under 60 that include information such as your earnings and estimated benefits. Instead, you are now encouraged to create an online My Social Security account.

But many individuals have yet to sign up. According to a March survey by MassMutual, 86 percent of individuals ages 50 to 59 have not created an account, despite the fact that they will no longer receive statements in the mail.

Leaving that undone can create an opportunity for identity thieves to set up an account in your name. And they may even try to claim benefits under your record.

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"If somebody has your Social Security number, then they would have a much easier time setting up an account under your Social Security number if you haven't already set up that access," said financial advisor Mark G. Smith, president of Vision Wealth Planning.

You may be especially at risk if your personal financial information has been compromised in an online breach. As many as 147.9 million consumers were affected when credit-scoring company Equifax unintentionally leaked private information last year — the largest breach on record.

"There's a pretty reasonable likelihood that the Equifax breach last year probably aggravated this," Smith said.