Eligible Dependent
A single person can claim the "amount for an eligible dependent" (equivalent to spouse) tax credit for a dependent child, at line 305 of the tax return.
This tax credit can also be claimed for a dependent grandchild, sibling, parent or grandparent. If the tax credit is being claimed for a dependent child, grandchild or sibling, the dependent must be either under 18 years of age, or dependent by reason of mental or physical infirmity.
A person may not claim this credit if, for the entire year, they have a spouse or common-law partner with whom they live, support, or are supported by. There are several conditions which must be met in order to claim this tax credit. For more information, see the Canada Revenue Agency (CRA) web page Line 305 - Amount for an eligible dependent, and CRA Interpretation Bulletin IT-513R Personal Tax Credits.