Last weekend I finally got around to filling out and mailing in my US census form. It was actually pretty simple and I feel a bit guilty about causing the government to waste money trying (unsuccessfully) to contact me in person. The problem is there is no real incentive to handle this in a timely manner and many people don't . In my case a quite modest incentive would probably have been sufficient (although it didn't help to have the form due at the same time as my taxes). However designing a suitable incentive doesn't seem simple. It can't be too expensive as you couldn't exclude people who would have returned the forms anyway. And you don't want people submitting fraudulent forms. Perhaps entering people who return their forms on time (and don't opt out) into a lottery would be a cost effective incentive.