Can we agree in a cohabitation agreement that neither of us will claim spousal support?

Yes, a cohabitation agreement can include a clause by which both partners waive the right to claim spousal support from each other. This is expressly permitted under Ontario's Family Law Act, which allows domestic contracts to address "the right to support." However, a court can set aside or vary a support provision in a domestic contract if doing so would result in conditions of serious hardship — this is a statutory override that cannot itself be contracted away.

The threshold for invoking this override is high, and courts generally respect freely negotiated domestic contracts. But if circumstances change significantly from what the parties anticipated when they signed (for example, a partner suffers a serious illness or disability that severely limits their ability to earn), a court might revisit the waiver.

This means a support waiver in a cohabitation agreement is not an absolute guarantee, but it is meaningful. The strongest waivers are those signed when both parties had independent legal advice, there was complete financial disclosure, the parties were financially independent at the time, and the agreement was reasonable in the context of the couple's situation. If one partner is financially dependent even at the time of signing, the waiver faces a higher risk of challenge.