Beginning tomorrow, thousands of census workers will be combing Hawai'i neighborhoods to assist people living at homes that have not returned a census questionnaire.

To date, 66 percent of Hawai'i residences have returned a census form by mail, compared with 72 percent nationally. That means the estimated 3,000 enumerators hired by the Honolulu and Wai'anae census offices will have to go door to door to try to account for the remaining 34 percent.

And, as occurs with each census undertaking, there will be more than just official enumerators making the rounds.

Already, local census offices and the Better Business Bureau have fielded reports of people posing as census workers trying to extract personal information from residents via phone, e-mail and in-person visits.

Census officials said Mainland offices are making follow-up phone calls to certain people who have already returned a census form. The purpose of these calls is simply to clarify or confirm information already submitted on the census questionnaire. Callers should not be asking for any information that is not related to the 10 questions on the 2010 Census form.

Census workers say census-related scams cause real problems for official census takers because some wary residents are unwilling to speak to anyone who comes to their door for fear that they will be victimized by identify theft. That limits the Census Bureau's efforts to get a complete count of the state, which in turn reduces the amount of federal funds earmarked for the state.

Here are a few things to keep in mind to tell the difference between an official census worker and a scam artist:

• Official workers will have an official census badge, a handheld device, an official U.S. Census Bureau canvas bag with census logo, and a confidentiality notice.

• Census workers will not ask to enter your home, and are not allowed to enter even if you ask.

• Census workers will only ask questions that are on the 2010 Census form. They will not ask for your Social Security number, banking information, immigration status, driver's license number or other personal information.

• Census workers may contact you by phone, mail or in-person visit but never by e-mail. If you receive an e-mail from someone claiming to be connected to the U.S. Census Bureau, do not open any attachments, as they may jeopardize your personal information.

• Census workers will not try to recruit you for census jobs on the spot.

• Census workers will not solicit donations.

If you suspect that you have been contacted by a scammer posing as a census worker, call your local census office or the Better Business Bureau.