Acting Taoiseach Enda Kenny has launched Census 2016.
The document, conducted by the Central Statistics Office, is used for a wide range of purposes including the development of public services.
It is also regarded as an important historical record.
The Census will take place on Sunday 24 April, the anniversary of the 1916 Rising.
Enumerators will begin delivering census forms today.
There are no new questions on the form, but an option to indicate whether a person is in a same-sex civil partnership has been added to the survey. Same-sex couples who are married will tick the 'married' box.
The Central Statistics Office says there was no budget available to carry out a public consultation, which may have resulted in new questions.
A senior statistician with the CSO said every person in Ireland on that night must, by law, be entered on a census form.
Speaking on RTÉ's Morning Ireland, Deirdre Cullen said the information is used to understand population changes and for planning infrastructure.
She said even if you are visiting another home on that night or staying in a hotel in the country you must be recorded as being there.
She said that those who fail to fill-in or be entered on a form will be prosecuted, adding that following the 2011 census, five people were prosecuted.
Traveller rights group Pavee Point has published an information section for Travellers and members of the Roma community on the Census on its website.
An information video in the Romani language is available on the website to encourage Roma people to complete the form and mark their ethnic group.
A Traveller specific video and information leaflet has also been produced.
The last Census in 2011 registered approximately 26,000 Travellers whereas the All Ireland Traveller Health Study carried out in 2010 by Traveller researchers registered 36,000 Travellers in the Republic.
