The federal Fair Debt Collection Practices Act dictates how and when a debt collector may contact you. In essence, the law says that you can't be harassed, threatened, verbally abused or lied to, no matter how much you owe or how many payments you've missed.

Here are the 10 things a debt collector can't do:

1. Call you before 8 a.m. or after 9 p.m. without your permission.

2. Use the phone to harass you, such as making repeated calls.

3. Call at work after being told your employer doesn't allow personal calls.

4. Tell your employer or anyone else that you owe money.

5. Call again after you've sent a letter asking the collector not to do so. The only exception is to tell you the collection agency is taking legal action against you.

6. Use obscene language or threaten to harm you.

7. Send you documents that appear to be legal papers when they're not, or state that forms sent to you are not legal documents when they are.

8. Imply that he is a lawyer, private detective, or credit bureau representative.

9. Imply that you have committed a crime or will be arrested if you do not pay your debt.

10. Threaten to sue if the collection agency does not actually plan to do so.

You may be surprised to know that the debt collector is allowed to contact other people about you -- but only to find out where you live, your phone number, and where you work. They can't harass your friends and family, so they are usually not allowed to contact each person more than once. Again, they can't tell anyone, except your attorney, that you owe money.

There are three other important things to know when battling collection agencies:

• If a collector crosses the line -- and some states impose stricter rules than the federal regulations above -- you can fight back. Click here to find out how to report bad collection agencies.
• You must receive a summons before you can be sued. If you receive a notice of judgment without having received a summons, complain to your state Attorney General. Then go to the court where the judgment was entered, tell them you were never served and want them to set aside the judgment.
• A debt collector may garnishee your pay -- instructing your employer to withhold a portion of your earnings until the debt has been paid. But federal law says no more than 25% of your after-tax income may be withheld and some states impose stricter limits. Collectors can never seize money you've received from Social Security or veteran's benefits.

For more information about what debt collectors can or can't do, visit the Federal Trade Commission Web site or go to the Privacy Rights Clearinghouse.

By Tracy Needham

Interest.com Contributing Editor

Have a question about your finances? Ask us at editors@interest.com