You want to protect yourself from identity theft, and you want to do more than just shred your documents.

Maybe you should lock up your credit file to keep the bad guys out.

There are lots of things an identity thief can do with your personal information. He can get a credit card in your name, open a bank account in your name or start cell phone service in your name. It can destroy your credit history.

One way to fight back: the security freeze.

I did it this week -- put a security freeze on my accounts at the big three credit bureaus, Experian, Equifax and TransUnion.

I did it online, but you can also do it by mail. It takes less than 5 minutes to put a padlock on each file.

"Anyone who is worried about the prospect of identity theft scrambling their financial situation and messing up their lives, there is no better thing you can do than freeze your credit report," said Joe Ridout of Consumer Action.

Of course, you can always unfreeze your file. That's why you can create a personal identification number when you put the freeze in place.

A permanent thaw can take up to three days, but you can get a temporary thaw in just 15 minutes to start cell phone service or to apply for a credit card.

Equifax and Experian charge Washington state residents $10 to place the freeze and $10 to thaw it. Right now, TransUnion will do both for free if you sign up online.

The freeze is free for Washington state seniors and anyone who is a victim of identity theft and can prove it with a police report.

So why a freeze; why not one of those credit monitoring services so many companies want to sell you?

"It'll let you know a little sooner if your identity has been stolen, but does nothing whatsoever to prevent identity theft. It's like buying life insurance after the body is cold. So anyone who's really worried about this prospect of ID theft should freeze their credit," said Ridout.

A credit freeze isn't for everyone. Shutting off access to your credit file can be inconvenient. And I know it won't stop all identity theft. Someone could still steal my social security number and do some damage. So I'll keep using the shredder.

But the freeze will make it much harder for an identity theft to commit a major financial crime that could hurt me.