Do we have to share our finances with each other before signing a cohabitation agreement in Ontario?

Yes. Financial disclosure is one of the most critical requirements for a cohabitation agreement to withstand challenge. The Family Law Act lists failure to disclose significant assets or debts as a ground for setting aside a domestic contract. If one partner hid or minimized assets before signing, the entire agreement — or the provisions affected by the non-disclosure — can be set aside by a court years later.

Full disclosure means each party should share a snapshot of their current financial situation: assets (bank accounts, investments, real estate, vehicles, business interests, pensions), liabilities (mortgages, loans, credit card debt, tax obligations), and approximate income. This does not need to be a formal audit, but it should be comprehensive and honest.

Many lawyers ask each party to complete a financial disclosure form and attach it as a schedule to the agreement. This creates a written record that both parties knew the financial picture at the time of signing. If you have concerns about privacy — for example, you own a business and do not want detailed financials circulating — your lawyer can advise on ways to satisfy the disclosure requirement while protecting sensitive information. The alternative — non-disclosure — puts the entire agreement at risk.