More than one in 10 Scottish homes have still not returned their census, new figures have revealed, weeks after the original deadline to fill out the form passed.

Some 86% of homes have returned the form, the National Records of Scotland (NRS) said on Saturday, with more than two million filling the once-in-a-decade census online and around 250,000 posting a paper copy.

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 May 1. 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 £9.76 million, bringing the total bill for the survey to £148m.

When he announced the new deadline, Mr Robertson suggested the Ukraine war and the pandemic could have affected the rate of return in Scotland, but stressed a high response was required to ensure the census is effective.

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 ten homes in Glasgow City and West Dunbartonshire had not returned the forms.

Householders who do not return the census may be prosecuted, the NRS said, 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 Second World War, 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.