The last census, held in 2001, was sharply criticised
Ministers will invade people's privacy by asking "intrusive" questions in the census, the Conservatives are claiming.
When the 2011 survey is conducted everyone in the UK will have to answer the questions or face fines.
Details will be sought about the number of bedrooms in people's homes and information about "overnight visitors".
The Tories said this would amount to "bedroom snooping" but ministers said all questions would be justified in the public interest.
The census, which is conducted every 10 years, is designed to give an accurate snapshot of demographic and social changes in the UK.
The 2011 survey is set to be carried out on 27 March 2011.
Officials are planning to introduce new methodology and ask a wider range of questions after the 2001 survey was sharply criticised.
For the first time, people will be asked to provide details of the number of bedrooms they have as well as the names, sex and birth dates of any overnight guests in their homes.
Other new questions include how well people can speak English, the date overseas nationals entered the UK, how people define their national identity and whether they are in civil partnerships.
Those who do not complete the census risk being prosecuted while those giving false answers face being fined.
The Conservatives said the nature of the some of the questions amounted to a breach of privacy.
"An increasingly invasive and intrusive census will erode public support, cost more and result in a less accurate survey," said shadow Cabinet Office minister Nick Hurd.
"These 'bedroom snoopers' are yet another sign of how the Labour government has no respect for the privacy of law-abiding citizens."
The details of the census must be approved by Parliament in advance.
The Office for National Statistics has published a list of specimen questions and said it does not expect any major changes to them.
Ministers have said the questions were decided following extensive consultation and take into account the importance of the information requested as well as whether it was acceptable to ask for it.