You are required by law to answer it. However I have read many times that they will not prosecute if you quietly ignore it and any subsequent letters, and quietly agree to comply whenever they visit in person. Your choices include (1) take 12 hours of your life to give them a bunch of accurate information that is none of their business but might help you, (2) take several hours of your life to give them truthful but not helpful answers, (3) completely ignore this without making a fuss, or (4) some other option.
Truthful but not helpful: make it a game of giving the least accurate answer that can by some logic be justified as responsive to the exact words of the question. As one example, if they want to know how many bathrooms have running water, the answer is “zero” because all the taps are turned off. No, you do not have a mortgage on THIS property because on the day you filled out the survey it was kept in your safe deposit box, your desk at the office, etc. Your race is HUMAN. The monthly condo fee? That’s what you pay times the total number of condos in the building, since you didn’t know they were only asking for your share of that fee. Your home would sell for $20,000 (a true statement, it would sell very quickly at that price). Your most important job activities are following the orders of your employer. It can be a lot of fun, but that’s just my thoughts.
If you’re really bored, you could compose the answers from words cut from magazine and newpaper articles and ads, taped to the form so it looks like a ransom note.
I choose (4) some other option. I’ll answer in person while cleaning my gun(s).
I also threw away the 2010 long form census I received. Got a knock on the door from a “temp” and he and I had a great time trashing the government. He did his “job” and asked the short form questions and then sat down with me over a beer while we talked about tyranny.
Can’t blame him, he was unemployed and just need the job.
Of course, now that I’ve admitted that, according to JOAT the NSA is coming after me now.