Nobody has ever been prosecuted for not filling out a census form. If you’re prepared to be firm, you will be bothered for a few months, and then they’ll go away.
“While big business benefits from having as much information about citizens as possible, many citizens are unwilling to give away their right to privacy. Hence, many are refusing to return the ACS. This automatically results in an additional form being sent, followed by a series of phone calls. In 21% of the cases, an unannounced, personal visit from a Census Bureau representative follows in a final attempt to get the survey completed. Often, more than one visit takes place.
In the end, however, the Census Bureau has no authority to enforce the laws that require the ACS be answered. The Census Bureau can press formal charges for non-compliance, but this is somewhat impractical given the number of forms that are not returned, or that are returned incomplete. A lawsuit would likely draw media attention and a public outcry that would very probably bring an end to the survey or end mandatory compliance. As of early 2007, no legal action has been taken against anyone for refusing to answer the ACS.”
There’s a lot of websites with people posting their experiences getting rid of these leeches. There’s a set procedure and time frame that they go by.
Here’s a couple links.
http://www.cxliv.org/2006/02/03/american-community-survey/
http://censusthis.wordpress.com/
Here’s an old manual describing their procedures for people who resist.
http://www.fcsm.gov/committees/ihsng/diffendalasa2000.pdf