Can we change our separation agreement after we have signed it in Ontario?

Yes, a separation agreement can be changed after it is signed, but both parties must agree to any changes. A variation must be made in the same way as the original agreement — in writing, signed by both parties, and witnessed. Verbal agreements to change a written separation agreement are generally not enforceable.

The most common reason couples revisit a separation agreement is a significant change in circumstances: income goes up or down, a child's needs change, one spouse remarries or cohabits, or the parenting arrangement in the agreement is no longer working. For child support specifically, the law allows either parent to apply to the court to change the amount if there has been a material change in circumstances, even if the agreement says it cannot be changed. Courts retain jurisdiction over child support regardless of what the agreement says, because child support is the child's right.

Spousal support terms can also be revisited, but unless the agreement expressly permits variation or the parties mutually agree, a court may be more reluctant to change what the parties negotiated unless the original terms have become unconscionable or circumstances have dramatically shifted.

If you want to change your agreement but your ex-spouse does not, you may need to apply to court.