Thieves got a goldmine of data when they stole 143 million Social Security numbers—along with names, addresses, and birth dates—belonging to Equifax customers. With it, they can steal property, money, get access to medical records, file fake tax returns, and wreak other havoc.

You might think an obvious way to protect yourself would be to change your Social Security number. But while you can easily change passwords, freeze accounts, and take other steps to keep your personal data secure, changing your Social Security number is complicated and not something anyone can do.

To make a change, you need a valid reason. Being a victim of identify fraud is an acceptable one, but you will have to submit proof that your current number is being misued and that the problem is an ongoing hardship. 

If you think you qualify for a new number, you'll need to keep records of anything that seems to indicate trouble, such as an IRS letter questioning you about income not reported, records of your frustrating battle to correct credit reports, or a letter denying you a mortgage because of erroneous information. If an identity thief filed a false tax return to steal your refund, that will certainly help your case.

If you have that information, you can get started by applying in person at a Social Security office. You'll need to complete the free application for an original Social Security card (Form SS-5). Here, you'll have to document the reason you need a new number, explaining how the old one has been compromised and how you have suffered.

You’ll also need to prove your citizenship and identity with a valid drivers license or a U.S. passport, birth certificate, or other acceptable document. 

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The SSA will review your application but may also look to see whether you've taken other steps first to resolve your problem, such as placing a security freeze on your account, which can help shut the door on a crook trying to access your credit report.

Once the application has been received, the agency will decide whether to approve your request for a new number. If it does, you should get it within 10 to 14 business days, according to Nicole Tiggemann, a spokeswoman for the agency.

But keep in mind that even if you are given a new number, your old Social Security number won’t go away. Instead, it will remained assigned to you and be linked to the new one.

The SSA will then send information about your new number to the IRS, your employer, and other federal agencies. But you may have to take on the task of updating others.

To make that process smoother, the Identity Theft Resource Center, a nonprofit organization established to support victims of identity theft, recommends that you get a letter from the SSA detailing the change and stating that you will no longer be using the old number. 

Be aware that because your credit history is tied to your Social Security number, getting a new number could indicate to some companies that you don’t have a credit history. That could happen, for example, if you apply for a mortgage or a credit card using your new number. In that case, you may have to explain that your Social Security number is linked to the older number that is connected to your credit-history data.