An estimated 1.8 million households are to complete census forms tonight to detail the State’s health, social and educational conditions.
The comprehensive forms were distributed over the last three weeks with residents legally obliged to fill them out or face a fine of up to €25,000.
The Government stressed it was essential that everyone is included in the study, to ensure decesions that will determine the country's future are based on accurate information.
Preliminary results will be available within three months, and principal demographic results within a year.
The form contains questions on the type of accommodation you live in, the type of heating and if you have an internet connection. Householders are also asked a raft of personal questions such as age, marital status, religion, ethnic background and education.
For the first time people will be asked to reveal the state of their health and what other languages are spoken in the home.
The information will be used to target state resources in education and health to support people who have difficulties with English.
The Central Statistics Office has stressed the census information will be kept confidential.
The forms were translated into 21 languages for those whose first language is not English, including Arabic, Bulgarian, Chinese, Czech, Estonian, French, German, Russian, Slovak, and Swahili.
The document is also available in large print and Braille.
Census 2011 is the 24th time the nationwide survey has been carried out. The last census was held in 2006.
PA