Households have until May 31 to complete the once-in-a-decade survey – the results of which are used to help make decisions on services across the country.
Some 86% of homes have returned the form, the National Records of Scotland (NRS) said on Saturday, with more than two million filling in the questionnaire online and around 250,000 posting a paper copy.
It comes after the deadline for completing the document was extended from the original date of May 1 – a move which added some £9.76 million to the bill for the exercise, bringing the total to £148m.
NRS chief executive Paul Lowe stressed the importance of completing the form.
He said: “It was great last week to cross the 85% response rate nationally – a major milestone in the census – and to see 25 local authorities exceeding their local target of 85%.
“I want to say a huge thank you to each and every household across the country who has done their bit.
“Tomorrow is the last chance for households to complete and submit their census. My message to those who have yet to complete is: don’t miss out. Don’t regret not taking part.
“Big decisions about our local communities and our nation as a whole are based on census data. Everyone’s circumstances need to be captured to ensure the best decisions are taken, so please complete now.”
Householders who do not return the census may be prosecuted, the NRS has said, and could be fined as much as £1,000.