Your Social Security number is one of the most sensitive pieces of personal information you own. Too bad yours (and mine and every other American’s) has likely been leaked and sold on the Dark Web.

Before you panic, there are a few steps you can take right now to protect yourself and your identity.

Is it really that big a deal?

It sure is. Your Social Security number is the key to the castle. It’s the unique identifier that connects your financial, government and personal records.

With your SSN, criminals can open credit card accounts, apply for loans, hijack your tax refunds, use your government benefits, or even apply for jobs.

There’s an easy step you can take

To safeguard your Social Security number, use the government's free Self Lock feature. This tool prevents your SSN from being used for unauthorized employment verifications. You'll need an E-Verify account to do this online.

You can also request a block by calling the Social Security Administration at 1-800-772-1213. Expect to wait on hold for a long time.

Stay proactive

The Social Security Administration also provides online access to your earnings and benefits history through its my Social Security account. It’s free to use and you can get an account even if you don’t receive benefits.

I recommend you check this once a year to make sure nothing is amiss. Check the reported income and confirm everything aligns with your actual work and benefits history.

Note that if you created a Social Security username more than three years ago, you’ll need to create a Login.gov account or use an ID.me account.

The reg flags

How do you know if your SSN is in someone else’s hands? Let me count the ways …

Unexpected bills or accounts: Receiving bills or statements for accounts you never opened is one of the most obvious signs someone is using your Social Security number. Thieves can use your SSN to open credit card accounts, take out loans, or even set up utilities in your name.

If this happens, contact the company immediately and report the fraudulent activity. At this point, a credit freeze is a must, too.

Tax forms that aren’t yours: If you get tax forms like W-2s or 1099s in the mail from employers you’ve never worked with, it could mean someone used your SSN to get a job. In this type of employment fraud, someone who may not otherwise pass employment checks uses your identity instead. It’s a mess and could leave you on the hook for their tax obligations.

Contact the IRS right away if you get any strange tax forms.

Tax filing goes awry: You file your taxes and then get a notice that someone else already filed using your SSN. This is a simple and surprisingly effective way for criminals to get refunds owed to you.

Act fast if you get a letter from the IRS about a duplicate filing. Go to IdentityTheft.gov to file a report. You may need to complete IRS Form 14039, the Identity Theft Affidavit, to officially report the incident.

Pro tip: Protect your tax accounts before this ever happens. The IRS offers a special Identity Protection PIN program. You get a six-digit number to use for filing your taxes, effectively locking your account to outsiders.

Hints on your credit report: I bet you see a theme here. Anything you know wasn’t you is the biggest sign. That can include new accounts, lines of credit you didn’t take out, or other unexplained changes to your credit.

You can get a free credit report once a year from each of the three major credit bureaus through AnnualCreditReport.com. Pro tip: Stagger the reports every few months to keep an eye on it more easily across the year.

Government benefit denials: If you’re denied benefits like disability, Medicare, unemployment, or other government assistance, someone may already be using your SSN to claim them fraudulently.

If it happens to you, reach out to the agency and explain the situation. They will guide you to the next steps to restoring your benefits.

Suspect your SSN was stolen?

Move quickly. Start with the Federal Trade Commission at IdentityTheft.gov. Fill out the form there, and you’ll get an entire plan for how to recover your identity and protect yourself going forward.

The IRS also has a place to report if you suspect someone is using your SSN: Identity Theft Central.

Check with your bank, credit card providers and insurance company, too. Some offer free fraud and identity theft protection services that can help you keep everything locked down.

The views and opinions expressed in this column are the author's and do not necessarily reflect those of USA TODAY. Learn about all the latest technology on the Kim Komando Show, the nation's largest weekend radio talk show. Kim takes calls and dispenses advice on today's digital lifestyle, from smartphones and tablets to online privacy and data hacks. For her daily tips, free newsletters and more, visit her website.