The Internal Revenue Service's online privacy policy states: "We do not use cookies, a file placed on a visitor's hard drive that allows the Web site to monitor the individual's use of the site," but the agency's home page does, indeed, create a cookie.

But it's a benign cookie. It expires in just four minutes, leaving nothing but an empty cookie entry. (If you lack a tool that lets you examine changes to your cookie file, you can see the entries at web-caching.com.

The site does use a cookie, admits Greg Carson, the IRS's director of Internet services. However, it's used as a session ID and to help optimize the site's load-balancing functions. The cookie, which expires after four minutes or when you close your browser, isn't used for tracking purposes. The IRS, which, like other federal agencies, is operating under a White House directive not to use cookies, had long debates about how to word its privacy policy, Carson says. Should it explain the difference between a session cookie and a persistent cookie? How many site visitors would make a distinction? The current wording was chosen, he says, because the agency wanted to focus on "what's the message we really wanted to get across? We don't use cookies to track what a user does."

Fred Wilf, a technology attorney at Morgan Lewis & Bockius in Philadelphia, points out that when users see a reference to cookies, they think of the technology rather than how it's being used. Even though the IRS hasn't violated its privacy policy, Wilf says, "Ambiguous statements like this, while probably not a violation of any statutes or regulations, demonstrate the difficulty in developing a privacy policy. The whole issue is how to provide legal protection and a service for consumers, while describing the underlying technology in an understandable manner."