A prenuptial agreement (or “prenup”) can be an important part of building a strong financial foundation in a relationship. However, not all prenups are created equal. In Canada, if a prenup isn’t made properly, it could be declared invalid by a court—which means that it won’t provide any protection at all.
This guide explains what makes a prenup invalid, common mistakes to avoid, and how you can protect yourself by creating an agreement that’s clear, fair, and enforceable.
Understanding the Basics of Prenuptial Agreements
What is a Prenuptial Agreement?
A prenuptial agreement (also sometimes called a prenup or a marriage agreement) is a legal document that couples sign before getting married. It outlines how property, debts, and financial matters will be handled during the marriage and if the marriage ends in separation or divorce.
Prenups are governed by provincial and territorial family laws across Canada, and each province has its own rules for what makes a prenup valid and enforceable.
Why Are Prenups Important?
Prenups help couples:
- Protect personal or family assets.
- Outline responsibility for debts.
- Reduce the risk of conflict and expensive legal battles if the relationship ends.
- Support fair financial outcomes in case of separation or divorce.
A well-prepared prenup provides peace of mind and clarity for both partners.
What Would Make a Prenuptial Agreement Invalid?
Several key issues can make a prenup vulnerable to being overturned by a court. Here’s what to watch out for:
Lack of Proper Disclosure
One of the main reasons a prenup can be invalidated is failure to fully disclose financial information.
Both partners must provide complete and honest information about:
- Income
- Property
- Debts
- Investments
- Future inheritance rights (if known)
If either party hides significant assets or debts, the agreement can be challenged and possibly set aside (meaning a judge won’t follow what it says if there’s a dispute). This is because an agreement made on the basis of false or incomplete information is unlikely to be seen as a fair agreement by a judge. Complete honesty is non-negotiable.
Coercion or Lack of Voluntariness
Prenups must be signed voluntarily, without pressure, threats, or coercion.
Signs of coercion could include:
- One partner being forced to sign shortly before the wedding.
- Threats to cancel the wedding if the prenup isn’t signed.
- One party being emotionally manipulated or not given time to review the agreement.
In Canada, a prenup signed under pressure is unlikely to be enforced by a judge.
Unfair or Unconscionable Terms
Courts can refuse to enforce a prenup if the terms are grossly unfair or unconscionable at the time of enforcement.
For example:
- One partner waives all rights to property or support without understanding the implications.
- The agreement leaves one partner in a financially devastating situation after a long marriage.
Canadian courts prioritize fairness, especially where major power imbalances exist. If one person earns the income while the other stays home to care for children, it is very unlikely that a court will consider it fair if a prenup does not compensate the person who gave up career opportunities for responsibilities at home through spousal support or a transfer of assets. A good prenup values the contributions of both partners to the success of the relationship – whether those contributions are financial or not.
Improper Execution or Missing Legal Requirements
A prenup must meet certain formalities, including:
- Being clear and in writing (verbal agreements are not valid).
- Being signed by both parties.
- Being witnessed properly, according to your province’s legal requirements.
Skipping any of these steps risks making the agreement invalid. To be even more certain of your agreement’s validity, each partner can have their own lawyer sign a certificate of independent legal advice. This proves that both partners knew and understood what the agreement meant before they signed it. We’ve included these forms as part of every Jointly agreement.
Including Invalid or Illegal Provisions
Prenups cannot include terms that:
- Determine custody or parenting arrangements in advance (only courts can decide the best interests of a child at the time of separation).
- Violate public policy or human rights laws.
- Limit a spouse’s rights in a way that is prohibited by law.
Adding invalid clauses can cause parts—or even all—of the agreement to be unenforceable. We recommend using Jointly’s platform or obtaining the services of a lawyer in your province to create your agreement to avoid this risk.
How Long Does a Prenup Last?
Do Prenuptial Agreements Expire?
In Canada, prenups do not expire automatically. Once signed, they remain in force unless:
- They are revoked by mutual written agreement.
- A court invalidates or sets them aside.
Prenups can also include clauses that require review or termination after a certain period. Couples can also revise them as needed. We recommend reviewing your prenup whenever you have a significant life change, to ensure that your agreement is still the right fit for both of you. We’ve included a review process with every Jointly agreement.
Ensuring Your Prenup Stays Valid
To keep your prenup strong over time:
- Review it periodically (especially after major life changes).
- Update it if necessary through an amendment or new agreement.
- Make sure both parties continue to understand and agree to its terms.
Proactive reviews help ensure the agreement stays aligned with your current circumstances, and helps to show that both partners continued to be on the same page throughout their relationship.
Common Mistakes to Avoid When Drafting a Prenup
- Waiting until the last minute: Signing a prenup too close to the wedding date can raise questions about pressure or fairness.
- Using vague language: Unclear terms lead to confusion and make it easier to challenge the agreement.
- Failing to update the prenup: A prenup should reflect current realities, especially after major life changes.
- Not accessing legal services: Without using Jointly’s platform or obtaining legal advice, it’s easier for a spouse to later argue they didn’t understand what they were signing.
How to Challenge an Invalid Prenup
If you believe a prenup you signed is invalid, you can ask the court to review it. This involves filing a claim (also referred to as commencing an action) with the court in your province.
Grounds for Contesting a Prenup
You may be able to challenge a prenup if:
- Your partner didn’t provide full financial disclosure.
- You were pressured or coerced into signing.
- You didn’t understand what you were signing and had no opportunity to get legal advice.
- The agreement is unconscionable or unfair based on today’s circumstances.
Each situation is different, and whether you are able to successfully challenge your prenup will depend on the specific facts of the case.
Seeking Legal Advice
If you think your prenup is invalid—or if your partner is trying to challenge it—it’s essential to speak to a family lawyer. A lawyer can help assess your agreement, explain your rights, and represent you in court if needed.
How Jointly Helps You Create a Valid Prenup
At Jointly, we make it easy to create a clear, fair, and legally valid prenup with our online platform, designed by lawyers, specifically for Canadians.
When you use Jointly, you get:
- Step-by-step guidance through the prenup process.
- Prompts for full financial disclosure, so you don’t accidentally leave something out.
- Clear explanations of what can and can’t be included under Canadian law.
Jointly empowers you to protect your relationship, your assets, and your peace of mind—without the overwhelming cost or stress of traditional legal services.
FAQs
Can you change a prenup after marriage?
Yes. In Canada, you can change a prenup after marriage by signing a new agreement or an amendment. Both partners must agree in writing, and the updated agreement should meet the same legal standards as the original.
Does a prenup have to be notarized?
Not necessarily. In Canada, a prenup doesn’t have to be notarized to be valid. Some provinces have specific requirements around independent legal advice. If you build your agreement with Jointly, we’ll walk you through the requirements for your province.
Can you write your own prenup?
It is possible to write your own prenup, but it is not recommended. As you’ve learned, there are a number of rules and formalities that must be followed in order for a prenup to be valid. If those aren’t followed, your prenup may not be enforced and will not provide any protection in case of a later separation. Why risk it? Jointly makes it quick, easy and affordable to create a legally valid prenup, entirely online on your schedule.
Ready to create a prenup that protects your future—and stands up to scrutiny? Click here to get started!
- Why Freelancers, Entrepreneurs, and Online Business Owners Should Get a Prenup - May 19, 2025
- Can I Protect My Assets Without a Prenup? - May 8, 2025
- What Makes a Prenup Invalid? - May 5, 2025
