Almost everything you read about preventing identity theft advises that you guard your Social Security number, or SSN, like gold. Why, then, do some agencies insist that you carry certain documents containing your SSN everywhere you go? And as one local consumer asked us, why when you call some companies does everyone who answers the phone need to know your SSN?

We know that identity thieves try all sorts of tricks to access our SSNs. With the numbers and some other personal information, they can open accounts or apply for jobs posing as you. They can also try to get a refund from the Internal Revenue Service; alert the IRS immediately if you receive a letter saying:

• The IRS has information you’ve been paid by an employer that you don’t know.

• It has received more than one tax return with your name on it.

The IRS will work with you to straighten things out. Of course, it’s simpler if you can avoid the hassle in the first place by keeping your SSN out of the hands of thieves.

That can be a problem if you carry it everywhere. Thieves are not shy about picking your pocket or handbag and helping themselves to your SSN, as well as whatever cash you might be carrying. For that reason, experts in preventing identity theft advise you to leave your Social Security card and other documents that contain your number at home, unless it’s mandatory that you have it.

That’s where the San Diego-based Privacy Rights Clearinghouse, or PRC, has a problem with some companies and government agencies. PRC notes that in 2006, the U.S. Government Accounting Office found that 42 million Medicare cards, eight million Department of Defense ID cards and seven million Veterans Affairs ID cards carried SSNs. It took until the middle of 2011 for the numbers to begin disappearing from the military IDs.

The Social Security Number Protection Act became law in December 2010, but will take three years to fully implement. Many consumers are unhappy that their SSNs appear on their Medicare cards, which they may feel obligated to carry. The PRC suggests you photocopy your Medicare (or other) insurance card and either blacken or cut out the last four numbers of your SSN. Cut the photocopy to wallet size and carry that, instead of your card with the full number on it. Once you’re in a database, that should be sufficient for identification or authentication purposes.

The “last four numbers of your Social” has become a theme song for entities that still use SSNs as identifiers. We’re asked to believe that revealing a partial number is not risky. Consumers Union, publishers of Consumer Reports, disagreed in a September 2007 letter to the Federal Trade Commission, saying “use of even a partial SSN may be an ineffective authenticator given the widespread availability of these numbers.”

During this tax season, identity thieves are sending out bogus emails by the millions, trying to trick us. Don’t give personal or financial information to a caller or email purporting to be from the IRS — the agency does not do business in those ways. And don’t click on anything in any unsolicited email.

For more on the subject, visit the Federal Trade Commission website at www.ftc.gov and search “tax related identity theft.”

Consumer Forum is a collaboration of the Bangor Daily News and Northeast CONTACT, Maine’s all-volunteer, nonprofit consumer organization. For assistance with consumer-related issues, including consumer fraud and identity theft, or for information, write Consumer Forum, P.O. Box 486, Brewer 04412, visit http://necontact.wordpress.com or email contacexdir@live.com.