The Office for National Statistics (ONS) has launched a consultation on whether the next national census could be carried out online, in a bid to deliver faster and more efficient data processing.

The previous census was carried out in 2011, which saw households filling out and returning lengthy, paper-based questionnaires.

An alternative approach using existing government data and compulsory annual surveys, albeit across a smaller proportion of households, is also being considered.

Peter Benton, the Beyond 2011 Programme Director, said: "Our population is changing rapidly, and we will always need good population statistics.

"There are different ways we could take a census in future, and they have different strengths and weaknesses. The best approach has yet to be decided, and this consultation will help us understand what matters the most."

An online census once a decade would be compulsory for households, with government data used to help check the quality of the final statistics. The 'once every 10 years' approach provides the ONS with a rich set of statistics for a range of geographic areas and is considered a familiar and tested method.

It also provides a high degree of continuity (the 2011 census was the 22nd one in England and Wales), which creates a single, high-quality snapshot of the nation. Moving it online would simply give the ONS an opportunity to take advantage of faster and more efficient processing of the data collected, compared with the time and cost of processing over 20 million paper questionnaires.

Also, the online responses to the 2011 census were found to provide higher quality data than the responses from the paper questionnaires.

However, the ONS recognises that not all households have access to the internet and an online approach risks excluding some people. Also, it claims that it is becoming increasingly difficult to achieve high levels of response to a census that takes place once a decade and imposes a burden on all households.

It will also be more expensive than the alternative approach of using government data, supported by smaller annual surveys, with an estimated cost of approximately £625 million over each 10 year period. This equates to £1.10 per person per year.

The alternative system of using data held by the likes of the Department of Health, DWP and HM Revenue and Customs, underpinned by a compulsory annual survey of around one percent of households to adjust for those not included in the administrative data, would cost £460 million over a 10-year period. This equates to about 80 pence per person per year.

Although this approach would allow ONS to identify changes and trends much more quickly, thanks to data being continuously updated, it would never produce as detailed statistics as an online census taken once a decade. The ONS states that it "would not result in the detailed historical record of people and households used by family historians and other historical researchers."

The consultation runs from 23 September to 13 December of this year and the ONS will publish its findings in 2014.