The return paperwork reports the sum of the previous year's (January to December) taxable income, tax credits, and other information relating to those two items.
The return is the method by which the Canadian government determines the appropriate amount of tax that should be paid by individuals and corporations.
[1] In generalised terms, a tax return refers to the yearly income declaration created by the taxpayer for every individual in the country.
Individuals and corporations who reside or conduct business in the province of Quebec also file separate returns with Revenu Québec.
In addition to tax purposes, the return plays a role in voter registration by including a checkbox asking if the signee if they are willing to have their personal contact information included on a national voter registry which is accessible by Elections Canada and its provincial equivalents.