Got a scary phone call saying you owe a lot of money to the Internal Revenue Service?

It is a scam.

Tax experts can say that with confidence, without knowing any of the details, because the IRS does not solicit payments by phone. It will not send e-mails. If the agency needs information from you, they write a letter first.

This does not stop scammers from telephoning millions of Americans to get personal information. And people keep falling for it.

In one scam still operating, 896,000 people have been called by would-be swindlers, and more than 5,000 victims have handed over $26.5 million, the IRS says.

Even tax accountants must work hard to avoid fraudsters in the run-up to the annual filing deadline, which is April 18 this year.

Here are four ways to avoid tax scams:

1. Shred, shred, shred

Be sure to shred all documents containing personal information, such as your Social Security number, home address, and birth date.

Spend a little extra and get a crosscut shredder, says Jeffrey Schneider, an enrolled agent for an accounting firm in Florida. That is because a straight-cut shredder is still tempting for thieves — they can take the shreds out of the garbage and piece them back together.

2. Follow the two Es

File early, file electronically.

"If you can beat the fraudster, they can't file on your behalf," said Jason Witty, chief information security officer for U.S. Bancorp.

A 2011 audit found that the IRS paid out $5.2 billion in refunds to scammers in 2011, even as it blocked about $6.5 million from getting into the wrong hands.

Filing electronically can help keep your financial information secure by making sure a paper document with your Social Security number, address, salary and bank account information does not get diverted through the mail.

3. Get smart about phishing

Tax scammers come at all angles.

Michael Kaiser, executive director of the National Cyber Security Alliance, said one new scam is an e-mail that seems to come from your payroll service, saying your W-2 form was compromised in a data breach. It asks you to click to find out how to protect yourself, and then once you do, it asks you for your Social Security number.

4. Know your relatives

Even if you avoid being taken to the cleaners by strangers, there could be dangers lurking in your own home.

"The truth is that a lot of ID theft is people who know each other," said Kaiser.

They will probably know where you store sensitive information and have answers to easy security questions like your first pet.

If you were counting on the IRS's 6-digit Identity Protection PIN, which uses a personal identification number to help lock out fraudsters, you are out of luck. The system was pulled down last week for a security review, according to the IRS. Security journalist Brian Krebs, who exposed some of the vulnerabilities on his website (krebsonsecurity.com), said the system has fundamental flaws based on the type of personal information it uses that is too easily bought for $2 a pop on the Internet.

"I doubt they'll bring it back," he said.

Beth Pinsker writes for Reuters.