Millions of procrastinating Americans will tackle their 2006 tax returns during the next few days, but the Internal Revenue Service says it’s ready for all of those last-minute electronic filers to hit the send button.

The IRS and a team of leading network vendors spend nine months of the year getting its popular Web site ready for the busy season, which this year will have run from Jan. 15 to April 17.

During tax season, IRS.gov is one of the Internet’s most heavily trafficked sites.

Click to see: Traffic on IRS site

The agency taps the expertise of Accenture, Qwest Communications, Akamai, IBM and others to keep IRS.gov up and running.

"The hit to our network infrastructure has been growing as fast as the number of electronically filed returns,’’ says Jimi Stricklin, deputy director of IRS portal program management. "Because of our traffic spike, we are trying to make sure our systems are refreshed and able to handle a load that’s increasing 9% every year overall. We definitely have to scramble to keep our systems up to date.’’

IRS.gov is seeing record traffic this year: It handled more than 90 million visits and 590 million page views from January through mid-March.

"We are up 9% year over year in visits, and 1.3% year over year in page views,’’ says Bert DuMars, director of electronic tax administration for the IRS. "A year ago at the same time, we had 82 million visits and 582 million page views.’’

The number of visitors to IRS.gov has been increasing 9% to 10% a year for the past five years.

The IRS and its vendors redesigned the site 18 months ago to make it easier for visitors to navigate. This has caused the number of page views per visit to plateau because visitors can find the information they need faster.

"We were seeing huge spikes in our search usage. We were up to 80 queries per second prior to the redesign,’’ DuMars says. "When we did the redesign, the number of search queries was cut in half. People are finding what they are looking for faster. If you do a good design, you get more efficient traffic.’’

In addition to IRS.gov, the IRS runs a private Web portal for tax preparers such as H&R Block and software vendors such as Intuit, which sells the popular TurboTax package. These organizations have secure, leased-line connections to the IRS, and they send batches of individual tax returns to the agency.