There is no credible information available on illegal immigration in Canada. Some estimates suggest that there may be up to 500,000 illegal immigrants in Canada. A further unsubstantiated claim is that most are refugee claimants whose refugee applications were rejected by the Immigration and Refugee Board of Canada.

If already in the country, Canada does not ask any type of immigration applicant to re-enter the country for any extension or approval of their status. This differs from the U.S. which insists on re-entry for most types of applications, and denies entry if an application is declined.

It stands to reason that there may be very few illegal immigrants who enter the country without first being admitted by the Canada Border Services Agency. The reason for believing this is that Canada is physically very difficult to get to, with the exception of crossing the Canada-United States border. And in this case, since the U.S. is itself a prime destination for illegal immigrants, not many illegal immigrants then attempt an unauthorized border crossing into Canada.

 Immigration categories

There are three main immigration categories:

Economic immigrants - Citizenship and Immigration Canada uses several sub-categories of economic immigrants. The high-profile Skilled worker principal applicants group comprised 19.8% of all immigration in 2005. In 2001 (the date of the last immigrant employment study) Skilled worker principal applicant landed immigrants had a 34% unemployment rate. Spouses and children of Skilled workers comprised an even larger percentage of the Economic immigrant category at 29.3% of all immigration.

Family class - Under a government program, both citizens and permanent residents can sponsor family members to immigrate to Canada. While this program has proven to be popular with recent immigrants, it has also been criticized by some for being too open-ended (i.e., a never-ending cycle of people related to yet more people which ultimately extends well beyond the original sponsor), a non-citizen can be a sponsor, and it allows retirees to immigrate who have not contributed significantly to the funding of the Canadian infrastructure, medical or social services system (the free rider problem). This category of immigrants also has a much lower labour force participation rate than economic immigrants.

Refugees - Immigration of refugees and those in need of protection. This immigrant population has a high unemployment record (51% in 2001) of an already small labour participation rate (44%), resulting in extended financial dependence on government assistance for the vast majority of refugees.

Under Canadian nationality law an immigrant can apply for citizenship after living in Canada for 1095 days (3 years) in any 4 year period.