A header file is the top section of the credit bureau file, containing name and address information and sometimes employment information but no information about creditworthiness. The header file was until recently considered public information;  the new Graham, Leach Act has changed that.  It is now necessary to have a "permissible purpose" under the Fair Credit Reporting Act to access credit bureau header information.

Thus under the new federal law, the Social Security Trace is regulated; it is now a restricted search under the Federal Credit Reporting Act.  (Note, that in addition, in California, state law requires that a notification footer be entered on the subject's credit report each time a Social Security Trace is run.) 

Despite the new law, and impostion of hefty penalties for violating it (up to a $5,000 fine and/or one year in prison), many unethical information brokers are willing to access headers for a price, with or without a strictly-defined permissible purpose.  (Admittedly, the new Graham, Leach law is somewhat fuzzy about what a permissible purpose is for header-info access, and even many seasoned private investigators and lawyers profess confusion on this point.  The best policy is probably to simply assume that header info is now on an equal ground with full-credit-report access; that is, only if you feel you have a permissible purpose for accessing the full credit report are you now safe in accessing header info. )

The Social Security Trace will nearly always provide the subject's current and past addresses, age, and indicate whether the subject has used more than one social security number in the past (a possible indication of fraudulent intent). Sometimes it will also provide his spouse's name. 

Important: The Social Security Trace is a private, not a public records, search, and requires the use of an information professional, who will charge a small fee for running the search through the three national credit bureaus. 

When available, this is probably the single most effective search available for locating missing persons. 

But what if you don't know your subject's social security number? Then you can run what's called a National Identifier. This search also uses credit bureau headers, but instead of searching on the basis of the subject's SSN, it uses his name and last known address. The National Identifier provides the same basic information as the Social Security Trace (including present and past SSN's), but the "hit rate" is somewhat lower. Since it utilizes credit bureau files, you need a permissible purpose under the FCRA, and an information professional who has a credit bureau account to run it for you. 

Here's what the header information you'll obtain from a Social Security Trace (or, generally, a National Identifier) looks like:

Scanning...Source #1 FOR SSN #111-11-111 

*Social Security Number Trace* DATE: 08/05/00; TIME 14:02 

1. JOHN DOE

123 ACORN STREET, CINCINNATI OH 45202 08/00 
AGE 29 
2. JOHN DOE

228 LINCOLN DRIVE, WASHINGTON DC 20224 02/98

 [etc., to include additional former addresses]
 

You should only utilize an information professional who has access to all three major credit bureaus to perform this search since the credit bureaus are regionally-focused, and unless you cover them all, you're omitting sections of the country from your search.