In Ontario, a prenuptial agreement, formally called a marriage contract under the Family Law Act, can be changed after marriage by entering into what is known as an amending agreement. This is a written document signed by both spouses that modifies specific terms of the original contract.

An amending agreement is subject to the same legal requirements as the original marriage contract, and if those requirements are not met, the changes may be unenforceable.

What Is an Amending Agreement?

An amending agreement is a separate legal document that sets out precisely which provisions of the original marriage contract are being changed, and how. It confirms that the remaining provisions of the contract continues in force.

An amendment is often preferable to replacing the entire contract, as it preserves the original terms that still reflect the parties’ intentions.

Legal Requirements for a Valid Amendment

To be enforceable under Ontario law, an amending agreement must: be in writing and signed by both spouses; be witnessed; be entered into voluntarily, without duress or undue influence; be supported by full and current financial disclosure from both parties; and be signed by both spouses. Independent legal advice is strongly recommended.

These requirements are designed to ensure that both spouses understand the legal and financial consequences of the changes, and that the amendment will withstand judicial scrutiny if challenged.

Common Reasons to Amend a Prenup

While every case is unique, some of the most common reasons for entering into an amending agreement include:
-Purchase of a new asset that the parties wish to treat differently than under the existing prenup (for example, a new home, cottage or investment property)
-Changes in business ownership or structure
-Reflecting a change in the parties’ intentions about how certain assets or debts will be handled in the event of separation or death

Strategic Considerations

Because a marriage contract is intended to provide certainty, amending it should be approached with care. In some cases, introducing a change to accommodate one event can have unintended implications for other provisions.

For example, changing how a newly purchased property is dealt with may affect the interaction between property division clauses and spousal support provisions. For this reason, it is common practice to have the lawyer drafting the amendment review the entire original agreement in light of the proposed changes.

Conclusion

Yes, you can change a prenup after marriage in Ontario, but only by entering into a properly drafted and executed amending agreement that meets all legal requirements under the Family Law Act. The amendment must be precise, supported by current disclosure, and carefully reviewed to ensure it achieves the intended outcome without undermining the overall agreement.

You’re Invited to Call or E-Mail!

If you’re changing a prenuptial agreement — or have already made your decision — you’re invited to call or email us. We’ll explain for free how you can protect your assets and plan your estate. You can call us toll-free at (800) 837-0460 or email us using our contact form here.