Does a common-law parent have to pay child support in Ontario?

Yes. Child support is a right of the child and is not affected by whether the parents were married or in a common-law relationship. Both biological and legal parents have an obligation to financially support their children, regardless of their own relationship status.

Child support in Ontario is calculated using income-based guideline tables — the Federal Child Support Guidelines for divorcing spouses, or Ontario's parallel Child Support Guidelines for common-law parents — both of which use the same income-based approach. The parent with less parenting time typically pays the table amount; if parenting time is substantially shared (roughly 40% or more each), the calculation can be adjusted.

Special and extraordinary expenses — such as childcare, orthodontics, or extracurricular activities — are shared in proportion to each parent's income in addition to the base table amount. If you separate from a common-law partner and share children, the same support framework applies as for divorcing spouses. Either parent can apply to the Ontario court to establish or vary a support order. Voluntary agreements are also enforceable when properly documented.