primarily responsible parent
The law says that the parent who’s “primarily responsible” is the one who takes care of their child on a daily basis. If both parents do this, it’s the parent who spends more time taking care of the child’s needs.
In a family with a female and male parent, the law considers the female parent to be primarily responsible. Same-sex parents or fathers who apply for the Canada child benefit may need a letter from the child’s other parent saying that they’re primarily responsible.