Two million households filled in their survey responses, but an estimated 700,000 have still to submit them.
Census letters were sent to 2.7million homes, representing 5.5million people
National Records of Scotland, which manages the 10-year survey, said anyone who failed to submit a response by 1 May could face prosecution – with a possible fine of up to £1,000.
In 2011, the last time the census took place, 95% of households replied.
But with a week to go until the deadline, the response rate is sitting at 74%.
Sunday 20 March was Scotland’s official Census Day. Householders were asked to answer questions for every person in the property relating to that day.
National Records of Scotland (NRS) said the information helps the government plan and fund services like transport, education and healthcare.
Households had the option to complete their census online, or to request a paper questionnaire and post it back.
NRS previously issued an appeal on 5 April, when more than a million households had still to complete a census.
Reminder letters were sent to every household in the country and field staff visited door-to-door.
Only about 300,000 further responses have been received since.
Scotland’s constitution secretary, Angus Robertson MSP, said it was essential for every household to complete the census as it was a “legal responsibility”.
He said: “I would ask everyone who has not submitted their census return to do so now. The information gathered is vital in shaping important services.
“We know that there are people who have begun the census online but haven’t completed it, and that others have requested a paper copy but haven’t yet returned it.
NRS chief executive, Paul Lowe, added: “Thank you to the two million households who have already submitted their response.
“For anyone that still hasn’t, help and support to complete your census is available on our website via our free helpline.
“Paper forms are still available on request for those who need them.”
A census has been taken every 10 years in Scotland since 1801, apart from in 1941 during the Second World War, and in 2021 due to the Covid pandemic.
Topics included household relationships, health, type of accommodation, age, and employment.
New questions in this year’s census included the use of British Sign Language, passports held, sexual orientation and trangender status.
England, Wales and Northern Ireland held their survey in March 2021. Anyone who has moved from another part of the United Kingdom to Scotland still has to complete the form.