What you need to know for the census

THE CENSUS: WHAT'S TO KNOW

* About two-thirds of Australians are expected to complete the five-yearly snapshot online - 12-digit logins have been snail-mailed out

* The ABS wants people to fill it out on Tuesday night but won't fine those who don't - it can be done any time in the next few weeks

* 1.8 million people have already got it out of the way

* Census staff will follow up with households that haven't returned a census until mid-September

* This year's snapshot has been mired in controversy after the ABS decided to keep names and addresses for four years

* But the agency says data will be encrypted en route to an internal storage system and cannot end up online

* Anyone who has lost their login shouldn't try to call the ABS on Tuesday because they won't get through.