People whose Census forms have not yet been collected have been asked to post it back to the Central Statistics Office.
Enumerators are now completing their collections and the CSO has urged people whose forms have not yet been collected to "post it without delay".
Returning Census forms by post is free of charge.
CSO Head of Census Administration Eileen Murphy said there has been a "great response from the public to the Census so far, with huge numbers of forms already collected by our numerators, but there is a small percentage that are still outstanding".
Speaking on RTÉ's Morning Ireland, she said that enumerators are finishing their contract at the end of this week, so a lot of this week is the tidy up, filing and administration.
"But they may be out collecting a few small number of forms, so if you happen to still have a Census form in your house, we're asking at this stage if you could please post it back to us," she said.
The address to send the form to is PO Box 2021, Freepost 4726, Swords, Co Dublin.
If a form has been lost or damaged, people can contact the CSO for a replacement form online or by calling 0818 202 04.
Ms Murphy said the CSO is already "gearing up" to start processing the forms, which will start as they come back in from the field.
She said the CSO hopes to have some preliminary headline results before the end of June, such as the population figures for the country, which she said is expected to be over five million for the first time since the 1850s.
