More than one in 10 Scottish homes have still not returned their census, new figures have revealed
National Records of Scotland (NRS) said 86% of households have completed the once-in-a-decade survey, weeks after the original deadline passed.
More than two million of them completed it online while about 250,000 have posted a paper copy.
The deadline for the census was extended by a month to 31 May because of the low completion rate.
Paul Lowe, chief executive of the NRS, urged people to complete their return.
"You only have until the end of the month to make sure that your voice is heard," he said.
"Census data is used to make important decisions on vital public services like schools, hospitals, housing and public transport, so filling it in really makes a difference to you, your family and your community."
The original deadline for Scots to return the form was set for 1 May.
After hundreds of thousands of homes had not returned the census, Constitution Secretary Angus Robertson told MSPs it would be delayed until the end of the month.
The delay has cost taxpayers £9.76m, bringing the total bill for the survey to £148m.
When he announced the new deadline, Mr Robertson said the Ukraine war and the pandemic could have affected the rate of return in Scotland.
However, others have suggested that decoupling the Scottish survey from the rest of the UK had reduced awareness.
Mr Robertson told BBC Scotland on Saturday that there were "lessons that need to be learned".
"Why is it that there are people who believe they have been uninformed or are underinformed about the fact that the census is taking place despite the fact that every household has been written to on numerous occasions during the census period?" he asked.
He pointed out that there had been advertising across the country and coverage in the media.
Mr Robertson added: "Still some people say they don't know there is a deadline going on."
Earlier this week the census passed an 85% return rate in 25 local authority areas, the NRS said.
These included Aberdeenshire, where 91% of forms had been returned, and the Scottish Borders, and Angus, where more than 88% of censuses have been sent in.
But according to the data released by the NRS on Thursday, around two in 10 homes in Glasgow City and West Dunbartonshire had not returned the forms.
Householders who do not return the census may be prosecuted and could be fined as much as £1,000.
This year's survey was the first principally digital census north of the border.
Mr Lowe said: "With over 89% of census returns being received this way, it reflects the popularity and acceptability of this innovative approach across the nation and will inform how we run the census in future."
As part of the drive to get people to fill in the form, there have been more than 1.58 million visits by field staff, 370,00 calls to the census call centre, and 65,000 emails and web chats answered, the NRS said.
A census has been taken every 10 years in Scotland since 1801, apart from in 1941 during the World War Two, and in 2021 because of the Covid-19 pandemic.
England and Wales held their survey in March 2021, when 97% of households completed the census.