The census provides information on the population of the UK every 10 years
Advertising campaigns to raise awareness of the 2011 national censuses are being launched later.The government measures the population of the UK 2011 every 10 years with a census in England and Wales, alongside separate surveys in Scotland and Northern Ireland.The form asks for detailed information including nationality, religious faith and marital status.
Census Day, when the snapshot of the nation will be taken, is on 27 March.
The Office for National Statistics (ONS) runs the census in England and Wales. In Scotland, the General Register Office for Scotland runs the census and in Northern Ireland it is overseen by the Statistics and Research Agency.
Jobs createdQuestions include national identity, ethnic group, educational qualifications, job titles, travel-to-work method and state of health.
For the first time there will be enquiries on civil partnerships, second homes and recent migration.
But there will be no questions on income, sexual orientation or the nature of any disability.
The majority of questions are the same or similar throughout the UK but the three surveys are customised to meet specific statistical needs.
It is compulsory to complete the census, and repeated failure to do so could result in a fine of up to £1,000. People can fill in their census form online for the first time.
The Office for National Statistics (ONS) said the information gathered would remain confidential for 100 years, and would not be shared with other bodies.
An ONS spokesman said: "It is not linked in any way to any other government department. All your personal information is kept completely confidential for 100 years.
"There is no chance of this being linked to the tax people, the police or anything else like that, or even the immigration authorities.
"We are not targeting illegal immigrants, we only want to get a true picture of the population in March 2011."
The census in England and Wales has created more than 35,000 jobs for the duration of the exercise, as advisers, co-ordinators, enumerators and collectors gathering information from 26 million homes.
But the project is expected to cost £482m - more than double that of the last census.
And there is speculation the 2011 census for England and Wales may be the last in its current form, with future data gathered from records held by the Post Office, local government and credit checking agencies.
An ONS spokesman said: "There is a working group within the ONS that is looking at a project known as Beyond 2011 and it is up to that group to make a report.
"The report will go to ministers and then it will go the Government to decide on what the future of the census is. No decision has been taken yet."