The free credit program will roll out nationwide, west to east, during the coming nine months. Free reports will also be available by toll-free telephone (877-322-8228) and by mail: Annual Credit Report Service, P.O.Box 105281, Atlanta, GA 30348-5281.

Last December, President Bush signed the Fair and Accurate Credit Transactions Act, which directed the three national credit bureaus -- Equifax, Experian and Trans Union -- to create a single, centralized source for all consumers to obtain one free credit report from each bureau, once every 12 months. The general assumption then was that consumers would order all three free bureau files with one request, once a year.

But in unveiling the Annualcreditreport.com site, the three bureaus added an unexpected, and potentially very useful, option for any consumer: You can order one bureau report at a time -- stretching out the process over a period of a year. That would allow eligible consumers, for example, to get their Trans Union report Dec. 1, their Equifax report next spring, and their Experian report next summer. That, in turn, would allow somebody who expects to buy a first home next year to take periodic free looks at his or her national credit files well in advance of applying for a mortgage.

Advance checks of credit reports represent a smart move for would-be home buyers since any -- or all three -- of their files may contain erroneous or missing key data that could raise the cost of a mortgage. The new website will not only allow you see your bureau files at no charge, but also will let you order credit scores, credit data tracking services and a variety of tools to protect yourself against identity theft.

To order a free credit report, you'll need to pass through an authentication procedure in which you are asked to supply information that an identity thief or hacker is not likely to possess. For example, the authentication procedure might ask you for details about a mortgage or car lease, though never your actual account numbers, according to credit bureau officials. You will definitely be asked for your Social Security number, but the site allows you to mask all but the last four numbers when your report is sent to you.

Each of the bureaus intends to make the most of the millions of expected visits to the site per month by promoting their own proprietary credit-related products. When you order your Equifax report, for instance, you'll be offered something the other two bureaus cannot sell -- your FICO score, at a cost of $6.95 per score. Equifax has an exclusive marketing arrangement with Fair Isaac Co., the developer of the FICO score. Experian and Trans Union, by contrast, will sell their own proprietary credit scores for around $4.00 per score.

All three of the bureaus will sell credit monitoring services that notify you of any significant changes to your file -- a sudden spurt of credit card applications, a rash of new inquiries by potential creditors, or a sharp drop in your credit score, for example. All of these credit file changes are associated with identity theft.

Experian's link to Annualcreditreport.com will introduce a novel advance on the monitoring concept starting Dec. 1: A "triple alert" service that scans all three of your national bureau credit files for even small changes or "pings" -- a single inquiry, an increase in debt on an account -- and notifies you electronically, by text message on your cell phone and by email. The cost of the service is $4.95 a month, with no minimum contractual number of months.