Date of Separation: Why Family Court and the CRA May Not Agree

One Separation, Two Different Dates

When a couple separates in Ontario, one of the first questions that arises is: what is the date of separation? The answer matters enormously. It affects property division, support obligations, tax filing status, and government benefits. But here is something that catches many people off guard — the date of separation for family law purposes and the date of separation for tax purposes are not necessarily the same.

Ontario family law and the Canada Revenue Agency apply different legal tests to determine when a couple has separated. Understanding the distinction is important for anyone going through a separation, because getting it wrong can have significant financial consequences.

How Ontario Family Law Defines Separation

Under section 4(1) of Ontario's Family Law Act, the date of separation is the date the spouses separate and there is no reasonable prospect that they will resume cohabitation. This is the "valuation date" for the purposes of dividing property through equalization.

There is no mandatory waiting period. A couple is legally separated as soon as the relationship has broken down and at least one spouse has formed the intention to live separate and apart. Critically, spouses do not need to live in different homes to be considered separated. Ontario courts have long recognized that couples can live "separate and apart under the same roof" — provided they stop functioning as a couple in all meaningful respects.

Courts look at a range of factors when the separation date is disputed, including sleeping arrangements, whether conjugal relations have ceased, financial separation, how the spouses present themselves socially, whether they share meals or household duties, and any communications expressing an intention to end the relationship.

In Kassabian v. Marcarian, 2025 ONCA 239, the Ontario Court of Appeal recently upheld a trial judge's finding on separation date where the wife's formal email communication of her intention to separate was treated as persuasive evidence — even though the husband claimed they had been sleeping in separate bedrooms for years before that. The case illustrates how nuanced these determinations can be.

How the CRA Defines Separation

The Canada Revenue Agency takes a different approach. Under the Income Tax Act, a person is considered "separated" only after they have been living apart from their spouse or common-law partner for a period of at least 90 consecutive days because of a breakdown in the relationship.

This 90-day threshold is mandatory. You cannot report a change in marital status to the CRA until those 90 days have passed. The good news is that once the threshold is met, the effective date of separated status is retroactive to the first day of living apart — not 90 days later.

The CRA also takes a stricter view of what constitutes "living apart." While family courts readily accept that spouses can be separated under the same roof, the CRA scrutinizes such arrangements carefully. Shared meals, shared finances, or shared parenting routines can disqualify a claim of living separate and apart for tax purposes.

The Key Differences at a Glance

The most important differences can be summarized as follows. First, family law has no waiting period — separation is effective immediately once the criteria are met. The CRA requires 90 consecutive days of living apart. Second, family courts are flexible about living arrangements and accept separation under the same roof. The CRA generally requires separate households. Third, the family law test focuses heavily on intention and the "no reasonable prospect of reconciliation" standard. The CRA test is more factual and focuses on whether the parties are actually living in separate residences.

Why This Matters in Practice

The gap between these two definitions creates real-world complications. Consider a few scenarios.

Property valuation: Under the Family Law Act, the equalization of net family property is calculated as of the separation date. If the date is disputed, the value of assets like a business, investments, or real estate could shift by tens or even hundreds of thousands of dollars. In one case we handled, a three-month difference in the separation date shifted a business valuation by over $150,000.

Tax filing: You cannot change your marital status with the CRA until 90 days have passed. This means there may be a period where you are legally separated for family law purposes but still considered married or common-law for tax purposes. Filing incorrectly during this window can trigger reassessments.

Government benefits: The Canada Child Benefit is calculated based on household income. Once the CRA recognizes the separation, the benefit amount is recalculated based on the lower-income parent's individual income — which often means a significant increase. But this recalculation does not happen until the CRA is notified and the 90-day threshold is met.

Child support: Under Ontario law, child support obligations begin immediately upon separation. There is no 90-day waiting period, and courts can order retroactive child support back to the separation date.

Practical Steps to Protect Yourself

Given these complexities, there are several practical steps anyone going through a separation should consider. Document the separation date clearly, ideally in writing — an email or text message to your spouse stating your intention to separate can serve as important evidence. Separate your finances as soon as possible, including bank accounts, credit cards, and shared subscriptions. If you must continue living in the same home after separation, keep meticulous records of your separate living arrangements for both family court and CRA purposes. Wait the full 90 days before notifying the CRA of your change in marital status, but do so promptly once the threshold is met. And seek legal advice early, because the separation date affects so many downstream issues — from property division to support to tax obligations — that getting it right from the start can save significant time and money later.

The Bottom Line

The date of separation is not a simple factual question with one answer. It is a legal determination that can be different depending on which body is making it and for what purpose. Ontario family courts and the CRA apply different tests, look at different factors, and impose different requirements. Understanding these differences early in the process is one of the most important things a separating spouse can do to protect their financial interests.