The Internal Revenue Service is cautioning taxpayers and tax professionals to beware of a new twist on an old scam in which fraudsters call up victims and threaten to cancel their Social Security number if they don’t pay their taxes.

“In the latest twist on a scam related to Social Security numbers, scammers claim to be able to suspend or cancel the victim’s SSN,” said the IRS in an email to tax professionals Thursday. “It’s yet another attempt by con artists to frighten people into returning ‘robocall’ voicemails. Scammers may mention overdue taxes in addition to threatening to cancel the person’s SSN. If taxpayers receive a call threatening to suspend their SSN for an unpaid tax bill, they should just hang up. Make no mistake…it’s a scam.”

The IRS warned taxpayers not to provide sensitive personal or financial information over the phone unless they’re positive they know the caller is legitimate. When in doubt, they should hang up the phone.

The IRS has begun using private collection agencies to help collect tax debts, but the IRS said the debt collection agencies will never call to demand immediate payment using a specific payment method such as a prepaid debit card, iTunes gift card or wire transfer (the IRS doesn’t use these payment methods). Similarly, legitimate IRS private debt collection agencies won’t ask a taxpayer to make a payment to a person or organization other than the U.S. Treasury, or threaten to immediately bring in local police or other law-enforcement groups to have the taxpayer arrested for not paying. They also aren’t supposed to demand that taxes be paid without giving the taxpayer the opportunity to question or appeal the amount owed.

Taxpayers who don’t owe taxes and have no reason to think they do should report the call to the Treasury Inspector General for Tax Administration and report the caller ID and callback number to the IRS by sending it to phishing@irs.gov. The taxpayer should write “IRS Phone Scam” in the subject line. They should also report the call to the Federal Trade Commission. When reporting it, they should add “IRS Phone Scam” in the notes.

Taxpayers who owe taxes, or think they owe taxes, can view their tax account information online to see the actual amount owed and review their payment options. Alternatively, they can call the number on the billing notice, or call the IRS at (800) 829-1040.