Your Social Security number is an important means of identification -- and it's also a piece of data you should make every effort to keep under wraps. But a new survey from VPN review site TheBestVPN reveals a very disturbing statistic: Roughly 22% of Americans are willing to sell their Social Security number for cash.

On the one hand, that may seem like an easy way to make a quick buck. But in reality, willingly giving up your Social Security number is one of the most dangerous moves you could ever make.

What happens when thieves get your Social Security number?

Your Social Security number is used to track your lifetime earnings to determine what benefits you may be entitled to down the line. For example, if you work long enough and pay enough Social Security tax, you'll be entitled to Social Security retirement benefits once your career ends. But that's not all -- your Social Security number is also used as a means of identification when you apply for a mortgage, credit card, and even a job. And if that number gets into the wrong hands, it could spell trouble.

Social Security card

IMAGE SOURCE: GETTY IMAGES.

For one thing, a criminal can use your Social Security number to open a new credit card on your account, rack up charges, and leave you on the hook for that debt. Furthermore, someone can use your Social Security number to file a tax return in your name, and then collect whatever refund you're entitled to.

If you're older, your Social Security number can be used to file a claim for retirement benefits -- only instead of that money going to you, it can be directed to a criminal's bank account instead. And the worst part? You may not even realize a benefit claim has been filed with your number until you go to do so yourself years later. At that point, the burden will be on you to prove to the Social Security Administration (SSA) that you're the rightful recipient of those benefits.

The takeaway? Keep your Social Security number guarded at all costs. That means knowing when not to give it out, and also, storing your Social Security card in a secure place (such as a home safe or safe deposit box at a bank, as opposed to your wallet, which could easily get lost or stolen since it leaves the house with you daily). There's no need to carry that card around with you unless you're specifically going someplace or doing something that may require you to submit it as identification.

Finally, don't even think about selling your Social Security number for cash, as the damage done to your finances will well exceed whatever near-term payout you collect. If you're truly cash-strapped, look into getting a second job to boost your income. And if you've already made the mistake of giving up your Social Security number, contact the SSA at once to request a new one. In some cases, the agency will give one out, and if you know yours is compromised, that's worth looking into.