The basic personal exemption in 2017 was $11,635. That person will be able to claim the Canada employment credit, so about $1,150, roughly; their CPP contributions; and their EI premiums. Probably they're not quite tax—it's pretty close. For a single parent, it would probably be a bit.... I think there would still be non-taxable.... It'll depend on the type. A single parent would be able to claim the eligible dependant credit, so...they'd have two basic personal amounts.
A video is available from Parliament.