The Canada 2011 Census is a detailed enumeration of the Canadian population on May 10, 2011. Statistics Canada, an agency of the Canadian government, conducts a nationwide census every five years. In 2011, it consisted of a mandatory short form census questionnaire and an inaugural National Household Survey (NHS), a voluntary survey which replaced the mandatory long form census questionnaire; this substitution was the focus of much controversy. Completion of the (short form) census is mandatory for all Canadians, and those who do not complete it may face penalties ranging from fines to prison sentences. 

The Statistics Act mandates a Senate and/or House of Commons (joint) committee review of the opt-in clause (for the release of one's census records after 92 years) by 2014. 

The 2011 Census is the fifteenth decennial census and is required by section 8 of the "Constitution Act, 1867". As with other decennial censuses, the data was used to adjust federal electoral district boundaries. 

As of August 24, 2011, Canada's overall collection response rate was 98.1%, up over a percentage point from 96.5% in the 2006 Census. Ontario and Prince Edward Island each hold the highest response rate at 98.3%, while Nunavut holds the lowest response rate at 92.7%.
What do all Canadian citizens have to fill out?
In 2011, it consisted of a mandatory short form census 