Markham Prenuptial Agreement Lawyer: Marriage Contracts and Cohabitation Agreements

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Nobody signs a prenup because they expect the marriage to fail. Markham couples sign them because a house owned before the wedding, a family business, an expected inheritance or children from a first marriage deserve certainty that Ontario's default property rules don't provide. Kazandji Law drafts marriage contracts and cohabitation agreements built to survive the only test that matters: a challenge, years from now, in a courtroom. Call 647-588-3234 for a free consultation.

By Fadi Matthew Kazandji, Founding Partner, Kazandji Law. Updated July 2026.

A Prenup by Any Other Name: Ontario Calls It a Marriage Contract

Prenup is the search term. The statute says marriage contract. Under Part IV of Ontario's Family Law Act, two people who are married to each other or who intend to marry may agree in advance on their rights and obligations under the marriage or on separation, annulment, dissolution or death (s. 52). Because the section covers people already married to each other, the same instrument signed after the wedding works too. There is nothing exotic about these documents. They are domestic contracts, the FLA's own category, sitting alongside cohabitation agreements and separation agreements.

Who signs them in Markham? The same patterns, over and over. One partner owns the house the couple will live in, often bought years before the relationship began. A family business or professional corporation needs to stay operable whatever happens to the marriage. Parents plan to gift or leave significant money and want it to stay on their child's side of the ledger. Second marriages carry children, existing obligations and hard-won caution. And couples who arrived from jurisdictions with very different marital property regimes want to choose their rules deliberately instead of inheriting Ontario's by default.

A marriage contract is not a bet against the marriage. It is the couple writing their own property rules while they still like each other, instead of leaving the drafting to two litigators and a judge at the worst moment of their lives.

What Your Contract Can Actually Decide

Section 52 lets couples contract about ownership in or division of property, support obligations, the education and moral training of their children, and any other matter in the settlement of their affairs. In practice, drafting maps a short list of worries onto clauses:

The worry	What the contract does
I owned this house before the wedding	Sets how the home's value is treated on separation, up to and including keeping its value out of equalization entirely. Possession is a different question, covered below
My business has partners, staff and debt	Fixes how the business is valued, excluded or bought out, so a separation does not turn into a shareholder crisis
My parents plan to help us buy, or to leave an inheritance	Reinforces the Act's treatment of gifts and inheritances and decides what happens if that money flows into a joint asset or the home
I'm worried about an open-ended support claim	Sets support amounts, formulas, time limits or waivers, subject to the court's override powers discussed below
I have children from my first marriage	Coordinates property and support commitments with your estate plan so both families' expectations are in writing

Equalization context explains most of those clauses. Married spouses in Ontario share the growth in their net worths between the wedding and separation: property brought into the marriage is generally deducted, and certain gifts and inheritances received during the marriage can be excluded. A contract does not have to fight that architecture. Usually it fine-tunes it: fixing valuation methods, confirming exclusions, or replacing pieces of the scheme with rules the couple actually prefers. The default regime itself, equalization, net family property and the rest, is covered across our Markham family law hub.

The Three Things No Ontario Prenup Can Do

Marriage contracts are powerful, and their limits matter just as much as their powers. Three stand out, and two of them surprise almost everyone who walks into our office.

1. It cannot sign away the matrimonial home's possession protections

Part II of the Family Law Act gives both spouses an equal right to possession of a matrimonial home while they are spouses, whatever the title says, and stops one spouse from selling or mortgaging the home without the other's consent. Under s. 52(2), a provision in a marriage contract that purports to limit a spouse's rights under Part II is unenforceable. What you can do is deal with the home's ownership and how its value gets treated in equalization. What you cannot do is contract away the right to live there, or the consent requirement for a sale, while the marriage is on foot. Possession and value are different questions, and careful drafting keeps them in separate clauses for exactly this reason.

2. It cannot decide parenting

The s. 52 menu includes the education and moral training of children, but it expressly excludes decision-making responsibility and parenting time. Parenting gets decided on the child's best interests at the time of separation, never by a bargain struck before the child was born. And under s. 56(1), a court may disregard even the education and training provisions where the child's best interests require it. If parenting is the real worry, the answers live on our Markham child custody page, not in a prenup.

3. It cannot make a support waiver bulletproof

You can waive or limit spousal support in a domestic contract, and courts usually respect the deal. But s. 33(4) of the FLA lets a court set aside a support provision or waiver, even a clear and carefully negotiated one, in three situations: where the provision results in unconscionable circumstances, where the dependant qualifies for support out of public money, or where support is in default when the application is made. Notice the first one targets unconscionable results, not just bargains that looked lopsided on signing day. In Divorce Act proceedings there is a second layer: the Supreme Court's Miglin decision governs the weight of final spousal-support releases in later claims. A well-drafted waiver holds in most of the lives a couple might actually live. A waiver sold as ironclad is an overpromise no honest family lawyer makes.

Why the Matrimonial Home Is the Whole Ballgame in Markham

Equalization normally lets you deduct what you brought into the marriage. The matrimonial home is the exception, and it is brutal: if the home you owned on the wedding day is still a matrimonial home when you separate, you get no date-of-marriage deduction for it. Its full value lands in your net family property and gets shared, even though you bought it years before you met your spouse.

Now put that rule in a market where the house is most families' largest asset. A Markham homeowner who marries and separates several years later can owe an equalization payment driven almost entirely by a house they already owned. Nobody chose that outcome; the statute chose it for them, and most people learn the rule only when it is too late to plan around it.

A marriage contract is the lawful fix. It can preserve the effect of a date-of-marriage deduction for the home, exclude the home's value outright, build a sharing formula that grows with the length of the marriage, or anything between. What it cannot touch, as covered above, is possession: the right to occupy the home and the consent rules for disposing of it stay intact while the marriage subsists (s. 52(2)). Value planned, possession protected. That division of labour is exactly what the Act intends, and it is the single most common reason Markham homeowners sit down in our Thornhill office before a wedding.

Written, Signed, Witnessed: Formalities That Are Actually Enforced

Section 55(1) of the FLA is short and unforgiving: a domestic contract, and any agreement amending or rescinding it, is unenforceable unless it is made in writing, signed by the parties and witnessed. No handshake deals. No kitchen-table documents with nobody watching. No chain of texts that adds up to a promise.

The same formalities apply every time you touch the document. Couples amend marriage contracts after a business sale, a new child or a reconciliation, and an amendment initialled in a hurry without a witness can unravel the careful work underneath it. We treat every amendment like a fresh signing: disclosure updated, advice documented, signatures witnessed.

Formal validity is the floor, not the ceiling. A contract can be perfectly written, signed and witnessed and still be set aside on the grounds in the next two sections. Think of s. 55(1) as the entry ticket, and the fairness rules as the actual game.

Building an Agreement That Holds: Disclosure and Independent Advice

The set-aside grounds in s. 56(4) double as a build checklist. Invert each risk and you get our drafting process.

• Full financial disclosure, documented. The first statutory ground is a party's failure to disclose significant assets, debts or other liabilities existing when the contract was made. So both parties exchange disclosure schedules, and the schedules attach to the contract itself. If the business is hard to value, the contract says so and records how the number was reached.
• Genuine understanding. The second ground is that a party did not understand the nature or consequences of the contract. Plain-language drafting, real time to read, translation where a party reads English poorly, and advice from that party's own lawyer are the antidotes. Each one gets recorded.
• No pressure. The third ground brings in ordinary contract law: duress, undue influence, unconscionability, misrepresentation. Timing is the classic trap. A contract first produced days before the wedding, with deposits paid and family flying in, reads like pressure whatever the parties intended.
• Separate lawyers. Independent legal advice is not a statutory requirement of validity, but its absence is a recurring theme in set-aside fights because it feeds the did-not-understand ground. We act for one party only, the other side retains their own counsel, and certificates of independent legal advice attach to the contract.

Ontario's own guidance to couples says the same thing in plainer words: agreements hold up when each side understood the terms, gave honest and complete financial information, and signed free of pressure. Build to that standard from the first draft, and the litigation risk drops to where it belongs.

How Prenups Get Attacked Later (and What Courts Actually Do)

Every challenge to a marriage contract in Ontario walks through a short list of doors. Section 56(4) lets a court set aside a domestic contract or a provision in it where a party failed to disclose significant assets, debts or other liabilities existing when the contract was made; where a party did not understand the nature or consequences of the contract; or otherwise in accordance with the law of contract. The analysis runs in two stages. The challenger must first prove a ground. Even then, the court decides whether setting the contract aside is the right exercise of its discretion. Losing stage one does not doom a contract; plenty of agreements with imperfect paperwork survive stage two.

The Supreme Court of Canada's message to judges leans toward respect. In Hartshorne v. Hartshorne (2004), the Court upheld a marriage agreement and cautioned that courts should be reluctant to second-guess arrangements couples made with independent legal advice, particularly where life unfolded roughly as they anticipated. The challenger's burden gets heavier where today's circumstances were reasonably foreseeable when the agreement was signed. One honest footnote belongs beside the citation: Hartshorne was decided under British Columbia's legislation of the day, not Ontario's FLA, so here it operates as a strong signal of deference while the actual mechanics run through s. 56(4), s. 33(4) and ordinary contract law.

Support releases carry their own extra framework. In Divorce Act proceedings, the Supreme Court's Miglin decision governs the weight of final spousal-support releases in later claims; we cover it in context on our Markham spousal support page. And some patterns invite attack no matter the doctrine: the contract first shown at the rehearsal dinner, the disclosure that quietly omitted a numbered company, the spouse who signed in a language they read poorly without advice. We build files to look boring to future litigators. Boring wins.

Living Together First? You Need the Cohabitation Agreement More

Common-law partners often assume they are covered by the same property rules as married couples. In Ontario they are not, and the gap is enormous. Equalization applies only to married spouses. Common-law partners own what is in their own name, and a partner who spent years contributing to the other's house or business must bring contribution-based claims after the fact, which means litigation, uncertainty and cost.

That is why s. 53 exists. Two people who are cohabiting, or intend to cohabit, and are not married may make a cohabitation agreement covering the same menu as a marriage contract: property, support obligations, education and moral training of children, and other matters, during cohabitation or on separation or death. For an unmarried couple the agreement is not a tweak to a default regime. It is the property regime, because without it there isn't one.

Support is the other half of the picture. Under the FLA, a common-law partner can owe or claim spousal support after three years of cohabitation, or where the couple has a child and a relationship of some permanence. A cohabitation agreement lets partners decide that exposure deliberately instead of discovering it at separation. Where children and child support enter the picture, the rules are not contractable in advance; our Markham child support page explains why.

And s. 53(2) holds the quiet conversion clause: if the parties to a cohabitation agreement marry each other, the agreement is deemed to be a marriage contract. The document follows you down the aisle. We draft every cohabitation agreement with the wedding in mind, because it may end up governing one.

Already Married? Contracts Signed Mid-Marriage

Section 52 covers people who are married to each other, so a marriage contract can be signed at any point during the marriage. Couples come to us mid-marriage when a business takes off and its partners or investors want marital exposure resolved; when parents advance serious money toward a home and the family wants the contribution recorded; when one spouse steps back from a career and both want the support consequences agreed rather than argued someday; and sometimes when a reconciliation needs terms each spouse can trust.

The framework is identical: same formalities, same disclosure discipline, same set-aside grounds. The negotiating dynamic is not. Married spouses already hold statutory entitlements, so a mid-marriage contract adjusts rights that exist rather than expectations that might never arrive, and courts scrutinize pressure claims with that in mind. Done carefully, a postnup is often the most honest financial conversation a marriage ever has.

How We Build Yours: Process and Timing

The rhythm is consistent. First, a free consultation to identify what actually needs protecting; plenty of worries turn out to be handled by the Act's default rules, and knowing that changes what we draft. Second, financial disclosure gets gathered and organized into schedules for both sides. Third, we draft, you review, and the terms move until they reflect a deal both partners would defend out loud. Fourth, the other party takes the draft to their own lawyer for independent advice, and you should expect real comments rather than a rubber stamp. Finally, signing: properly witnessed, certificates attached, comfortably before the wedding rather than the week of it.

Start when the date is set, not when the invitations go out. Disclosure takes time, the other side's lawyer needs time, and distance from the ceremony is itself legal protection, because pressure is a set-aside ground. One more constant: we act for one party only. The contract's durability depends on both sides being genuinely and separately advised, and we protect that structure even when couples ask to share a lawyer to save money.

If the Contract Ends Up in Court

Marriage contracts are signed in lawyers' offices and challenged in courtrooms. For York Region families that courtroom is the Newmarket Family Court Branch at 50 Eagle Street West, and a set-aside claim rarely travels alone. It usually arrives packaged with equalization and support claims in the same application, because the contract is the obstacle standing between the challenger and the statutory scheme. The court deals with the s. 56(4) attack first; whatever survives frames everything that follows, from property to support. Our Markham divorce page walks through how those applications actually run.

Two practical notes. A separation agreement signed at the end of a relationship is a different instrument with its own battleground, covered on the spousal support page. And a challenged contract does not have to mean a trial: set-aside disputes settle in mediation constantly, and our Markham family mediation and ADR page maps those routes, including mediating changes to a contract both spouses have outgrown. Either way, move early. Positions harden fast once an application issues.

Six Prenup Myths That Cost Markham Couples Real Money

Myth one: prenups are for rich people. The math says otherwise. The couples with the most to lose under Ontario's default rules are ordinary homeowners, because the matrimonial home rule takes away the date-of-marriage deduction that every other asset receives. If one of you owns a house or a condo going into the marriage, you are exactly who Part IV was written for.

Myth two: asking for one means you are planning the divorce. A marriage contract is closer to insurance than to prophecy. People insure homes they fully intend to keep. The document also does quiet good on the way in: expectations get named, finances get disclosed, and more than a few clients tell us the negotiation was the most honest money conversation the relationship had ever had.

Myth three: a prenup can cover everything. It cannot touch possession of the matrimonial home (s. 52(2)), it cannot decide parenting, and it cannot make a support waiver immune from s. 33(4). Anyone promising total coverage is describing a document Ontario law does not permit.

Myth four: courts ignore prenups anyway. The opposite is closer to the truth. Hartshorne signals deference to agreements built on advice and disclosure, and s. 56(4) is a targeted list of defects, not a general licence to rewrite deals that turned out to be inconvenient. Contracts fail for buildable reasons: hidden assets, missing advice, pressure at the altar. Build those out and the contract stands.

Myth five: one lawyer can act for both of us and save money. Sharing a lawyer is how contracts die a decade later, because it hands the future challenger a ready-made argument that nobody explained the deal to them. We act for one of you, the other retains independent counsel, and both certificates attach to the document.

Myth six: we are already married, so it is too late. Section 52 covers existing marriages. Mid-marriage contracts are routine where a business takes off, family money arrives or a couple reconciles on new terms.

Every myth traces to the same root: treating the contract as a form instead of a file. Treat it as a file, with disclosure, advice and time, and it does exactly what you hired it to do.

Why Kazandji Law for Your Marriage Contract

Plenty of services will sell you a template. We build contracts the way litigators read them, because a litigator is eventually who reads them.

• Drafted against the set-aside grounds. Every file is built assuming a skilled lawyer attacks it in fifteen years: disclosure schedules attached, advice documented, timing kept clean.
• Family law depth on both ends. The same team litigates equalization and support disputes at Newmarket, so we know which clauses fail and why. Explore the full practice at our Markham family lawyer hub.
• Honest scope. We tell you what a contract cannot do, including parenting and possession of the home, before you pay for promises the Family Law Act will not keep.
• Four offices. Toronto headquarters at 180 John St, Unit 320; a Thornhill office at 7191 Yonge St, Suite 310, minutes from Markham and serving all of York Region; plus North York and Oakville locations.
• One side only. We act for you alone and insist the other party gets real independent advice, because that discipline is what makes your contract durable.

This page is general legal information for Ontario couples, not legal advice about your situation. Statutory references are to Ontario's Family Law Act as it stands in July 2026; case references are to the decisions named. Every relationship and every contract is different: get advice before you sign anything. Kazandji Law, 180 John St, Unit 320, Toronto, ON M5T 1X5 · 647-588-3234.