I got one of those once and threw it away. They sent me several letters saying I needed to fill it out. I threw them away.
Finally they started calling. I ignored their calls until I picked up the phone without letting the answering machine screen the call because I was expecting a call from a friend and they were on the line.
The woman said I needed to send in my survey. I told her I had no intention of sending it. She asked me to talk to the supervisor. I told the supervisor that I don't answer surveys. She said; "But this is for the government." I told her I didn't care who it was for, I didn't answer surveys. After about 5 min she said OK but because it was computerized I’d keep getting forms for a few months.
They sent out a few more letters and I never heard from them again.
In 2000 I got a long form and only answered how many people were in the family. For a few months people came knocking on the door at different hours now and then and I never answered it if I looked out and didn't know the person. That harassment stopped after a time and I have yet to fill out a more than the number of people in my family.
I’ve heard from several sources that virtually no one has ever been penalized for not answering the entire form. An earlier poster was right - the publicity firestorm it would start would backfire on big government big time. I almost hope they will do it.