It just happened.
I couldn’t remember the name of the form as I lost it. So I goggled Census and the Long Form looked like the right one and the version on the Net was dated January 1, 2000.
Subsequently, responders let me know it was actually the Community Service Form.
I researched the survey online when I got it and the consensus there was that they chase you for about 2 months before giving up.
So we decided to not fill it out. Sure enough, they visited us, called us, etc for about 2 months and subtly threatened that there would be repercussions for not filling it out.
We were evasive with them..."we don't have time", "we're travelling next week", etc. They say they'll sit down with you and help you, etc.
Eventually almost to the day that the 2 months were up they quit harassing us.
NOTE: There is no record of them EVER following through with the penalty. The survey is riciculously intrusive.