Tracing an Inheritance Mixed With Family Property in BC

Author: SiLaw Group Family Lawyers
Published: Aug 10, 2026

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An inheritance arrives during a marriage. It goes into the joint account, pays down the mortgage, or funds a renovation. Years later, the relationship ends, and a hard question surfaces: how much of that money is still "yours," and how much must be shared? In February 2025, the BC Court of Appeal gave its most direct answer yet in Mills v. O'Connor, 2025 BCCA 34 — the first time the court has set out specific guidance on how to trace excluded property that has been co-mingled with family property.

Excluded Property and the Burden of Proof

Under BC's Family Law Act, most property either spouse owns when they separate is family property, and the starting point is that spouses share it equally. Some property is excluded. Broadly speaking, that covers what a spouse owned before the relationship began, along with certain assets received during it — such as gifts and inheritances given to one spouse alone. The thinking behind the regime is often put simply: spouses keep what was theirs, and share what the relationship built.

Two points catch people off guard. First, the growth in value of excluded property during the relationship is itself family property. The exclusion protects the original value, not the gains. Second, the spouse who claims an exclusion must prove it. If the original value cannot be followed into something that still exists at separation, some or all of the exclusion may be lost.

What "Tracing" Means

Tracing is the exercise of following value from one asset into the next. When an inheritance sits untouched in its own account, or is used on its own to buy a single asset, the trail is easy to follow. The hard cases arise when value is co-mingled — blended with family money in a joint account, rolled into the family home, or cycled through a series of purchases funded partly by excluded money and partly by shared money or debt. Once the dollars are mixed, no one can honestly say which dollars bought what.

The Problem With "First In, First Out"

For a long time, one answer came from an old line of trust and banking cases: treat the mixture on a "first in, first out" basis, so whoever contributed first is treated as taking value out first. Canadian courts have largely rejected that method as arbitrary, because it turns on timing and luck rather than fairness. In the family law setting, the Court of Appeal observed that this style of reasoning tends to treat excluded property more favourably than family property — it quietly assumes the excluded money survived every transaction intact while the shared value absorbed the losses.

Mills v. O'Connor: The Court of Appeal's Answer

In Mills, the husband inherited a house from his parents during a marriage of more than 20 years. He later sold it, and the proceeds went into buying land and building a family summer home. After the spouses separated, that home was destroyed by fire, and by the time of trial the insurance money was sitting in trust. The trial judge treated the full original value of the inheritance as surviving intact into those funds, describing the analysis as following a "bouncing ball" from one transaction to the next.

The Court of Appeal held that this was an error of law. Following the ball from the inheritance forward, undiminished, was first-in-first-out tracing in effect. Because the increases in value along the way were family property, the mixture contained both excluded and family value — and neither category is entitled to preferred treatment.

The court's general rule is pro rata tracing. The excluded value and the family-property value that were blended together are treated as proportionate contributions to one mixed pool, and whatever remains at trial is attributed in those same proportions. The court preferred the simpler version of this method — compare each contribution against the total of all contributions, then apply those proportions to what is left — over a forensic, transaction-by-transaction accounting, which it reserved for rare cases. It also stressed that tracing in family cases should stay flexible, and that a different method may occasionally produce the fairest result.

One reassuring note: pro rata tracing only reduces an exclusion below its original value where the mixed pool has dropped in value. If the pool held its value or grew, the original excluded amount is not cut down by this exercise — the growth was simply never excluded in the first place.

What This Means in Practice

• Records decide these cases. Estate documents, account statements, and purchase records are what make tracing possible, and the burden of proof sits with the spouse claiming the exclusion.
• Keeping an inheritance in a separate account, in your own name, remains the cleanest way to preserve an exclusion.
• Mixing does not automatically destroy an exclusion. It changes the math, and it raises the stakes on evidence.
• The analysis is technical, and the fair method can vary with the facts. Early advice can shape how you hold property long before any dispute begins.

Where to Go From Here

If you have received an inheritance, brought property into your relationship, or are sorting out what is shared and what is excluded, we can help you understand how these rules apply to your situation. Learn more about property division, or Book a free consultation with our South Surrey team.

This post is legal information, not legal advice.