Can we write our own cohabitation agreement without lawyers in Ontario?

Technically, the Family Law Act requires only that a domestic contract be in writing, signed by both parties, and witnessed — it does not explicitly require a lawyer. So a self-drafted agreement could meet the basic formal requirements.

However, there are significant practical risks to going without independent legal advice. The most common reason cohabitation agreements are set aside by Ontario courts is that one party later argues they did not understand the nature and consequences of the agreement, or that there was no meaningful financial disclosure. When neither party has legal advice, both of these arguments become much easier to make. A court can disregard the entire agreement, leaving you in the same position as if you had never signed one.

Additionally, self-drafted agreements often contain ambiguous language, miss important issues specific to the couple's situation, or include clauses that are unenforceable under Ontario law. The cost of having each partner obtain independent legal advice before signing is modest compared to the cost of litigating a dispute over a defective agreement years later. If cost is a concern, some lawyers offer flat-fee domestic contract review services.