Cohabitation Agreement or Prenup? What Alberta Couples Get Wrong

Ask ten Alberta couples what separates a cohabitation agreement from a prenup, and you’ll get ten different answers. Most of them will be wrong. Some think the two documents are basically the same thing with different names. Others assume that if they’re not walking down an aisle, they don’t need either one. Both assumptions can cost a person their house, their savings, or years of their life in court.

The truth is simpler than the confusion suggests – but it depends on two things most people never think to check: what stage your relationship is at, and what Alberta law already assumes about you.

Two Documents, Two Starting Points

A prenuptial agreement – sometimes called a marriage agreement or family property agreement – is signed by two people who are planning to marry. It sets out how property, debt, and support will be handled if the marriage ends, instead of relying on the default rules under Alberta’s Family Property Act. It only takes effect once the marriage actually happens.

A cohabitation agreement does the same job, but for couples who are living together without getting married, or who plan to. It’s built for people who are – or are about to become – what Alberta law calls Adult Interdependent Partners (AIPs).

On paper, that’s the whole distinction: one is for people getting married, the other is for people who aren’t. In practice, most Alberta couples get the harder part wrong – figuring out which one actually applies to them, and when.

The Myth: “We’re Not Married, So None of This Applies to Us”

This is the mistake that costs people the most.

Since January 1, 2020, Alberta’s Family Property Act treats Adult Interdependent Partners the same way it treats married spouses. If you’ve lived together for three years in a relationship of interdependence – or less than that if you share a child together and live in a relationship of some permanence – you’re an AIP whether you’ve ever discussed it or not. And once you’re an AIP, the same 50/50 presumption that applies to married couples applies to you: most property acquired during the relationship gets split equally if it ends.

Couples who’ve been together for years, bought a house together, and never once used the word “common-law” are frequently stunned to learn they’ve met the legal test for AIP status – sometimes without either of them consciously deciding to. By the time they find out, it’s not a planning conversation anymore. It’s a dispute.

The Myth: “They’re Basically the Same Thing”

Structurally, yes – both documents can address property division, spousal support, and what happens to the family home. But timing changes everything about how, and whether, each one applies.

A prenup signed before the wedding doesn’t take effect until the marriage happens. A cohabitation agreement is meant to apply while you’re living together – but its relationship to your legal status as an AIP is more delicate than most templates let on. Sign it too early, in the wrong way, or without the right legal advice, and it may not hold up when you actually need it. (We’ll dig into that specific trap in a future post – it catches more Alberta couples than you’d think.)

The bottom line: which document you need isn’t about how committed you are. It’s about your legal status, and when that status kicks in.

What Actually Makes Either Agreement Hold Up in Court

Alberta doesn’t let a downloaded template or a handshake agreement do this job. Under sections 37 and 38 of the Family Property Act, an agreement dividing property is only enforceable if:

• It’s in writing.
• Each partner acknowledges – separately from the other – that they understand what the agreement means and does.
• Each partner acknowledges they’re aware of the property claims they could otherwise make, and that they’re giving those up.
• Each partner signs freely, without pressure from the other.
• Each acknowledgment is made in front of a lawyer who isn’t representing the other partner.

That last point is the one people skip, and it’s the one that matters most. Both partners need their own lawyer – not one lawyer explaining the agreement to both of you, but two separate lawyers, each looking out for one side. Skip that step, and the agreement you thought protected you may not survive a challenge.