Yes, as of June 2026, you can legally hire a licensed private investigator in Ontario to gather evidence that your former spouse is cohabiting with a new partner. If proven in the Superior Court of Justice, this can be grounds to reduce or completely terminate your spousal support payments.
Paying spousal support after a separation is designed to help a lower-earning spouse maintain financial stability. Most final Separation Agreements and court orders in Canada include a “material change in circumstances” clause. One of the most common triggers for ending or reducing support is if the receiving spouse begins living with a new romantic partner in a marriage-like relationship. However, ex-spouses who want to keep receiving their monthly cheque will sometimes go to great lengths to hide their new living arrangements.
If you suspect your ex is secretly cohabiting, simply telling a judge “I know they live together” is not enough. 📸 Family courts require hard, admissible evidence. This is where a licensed private investigator (PI) becomes an invaluable asset. A professional investigator knows how to legally document daily routines, vehicle movements, and overnight stays without violating privacy laws. This guide explains how PI evidence is used to terminate support in Ontario.
Step-by-Step Process for Investigating Cohabitation in Ontario
Whether you are dealing with a support case in Toronto, Hamilton, or London, the rules of evidence in family court are strict. Most individuals who suspect fraud work closely with their family lawyer to hire a PI, ensuring that the investigation remains completely legal and compliant with the Personal Information Protection and Electronic Documents Act (PIPEDA).
Step 1: Reviewing Your Legal Order
Before spending money on an investigator, your lawyer must review your Separation Agreement or Divorce Order. 📄 Some agreements state that support ends immediately upon cohabitation. Others state that support is only reviewed after the new couple has lived together continuously for one or two years. You must know what legal threshold you are trying to prove.
Step 2: Hiring a Legitimate PI Agency
In Ontario, a private investigator must be licensed by the Ministry of the Solicitor General. Do not ask a friend to follow your ex. An unlicensed person’s evidence can be thrown out of court, and they could face harassment charges. A licensed PI agency knows how to conduct covert surveillance strictly from public property, ensuring the evidence holds up before a judge.
Step 3: Conducting the Surveillance
The investigator will usually conduct random spot checks over several weeks or months. 🚗 They will document if the new partner’s car is consistently in the driveway overnight, if they have a key to the home, or if they are performing household chores like mowing the lawn or taking out the garbage. Cohabitation in family law is not just about sleeping in the same bed; it is about functioning as a single economic and domestic unit.
Step 4: The Investigator’s Affidavit
Once enough evidence is gathered, the PI will draft a comprehensive, sworn Form 14A Affidavit. This document details dates, times, and observations, usually accompanied by date-stamped photographs or video links as exhibits. Because the PI is an independent, licensed third party, judges give their affidavits significantly more weight than the angry allegations of an ex-spouse.
Step 5: Filing a Motion to Change
With the PI’s affidavit in hand, your lawyer will file a Motion to Change (Form 15) at the Superior Court of Justice. 🖞 You are formally asking the judge to declare that a material change in circumstances has occurred and that your spousal support obligations should be lowered or terminated entirely, and sometimes even retroactively refunded.
How Much Does it Cost in Ontario?
Investigating cohabitation is a front-loaded expense. You must pay for the surveillance before you can file the court motion, but it can save you tens of thousands in future support payments.
| Expense Type | Estimated Cost (CAD) |
|---|---|
| Licensed Private Investigator | $100 – $175 / hour + mileage |
| Typical Surveillance Retainer | $2,500 – $5,000 (For a standard investigation) |
| Lawyer Drafting Motion to Change | $2,500 – $5,000 |
| Contested Court Hearing | $5,000 – $15,000+ |
How Long Does the Process Take?
Proper surveillance cannot be rushed. It usually takes a PI 4 to 8 weeks to establish a undeniable pattern of cohabitation rather than just a weekend visit. Once your lawyer files the Motion to Change, it generally takes the Ontario court system 6 to 12 months to schedule a hearing and issue a new support order.
Frequently Asked Questions (FAQ)
Can a PI put a GPS tracker on my ex’s car?
No. Under Canadian law, placing a GPS tracker on a vehicle without the owner’s consent is generally illegal and constitutes a criminal offence. Professional PI agencies rely on visual tracking and public observation.
Is spending three nights a week together cohabitation?
Not necessarily. Ontario courts look at multiple factors to define a “marriage-like” relationship, including shared finances, social interactions as a couple, and domestic chores. Simply dating and having sleepovers does not always meet the strict legal definition of cohabitation.
Will my ex have to pay my PI fees if I win?
It is possible. If the judge finds that your ex-spouse intentionally lied about their living situation to fraudulently collect support, the court may order them to reimburse you for your private investigator costs as part of a formal costs award.
What if my ex claims the new partner is just a roommate?
This is a common defence. If they claim it is a roommate situation, your lawyer can use the discovery process to request copies of their lease agreement, rent e-transfers, and shared utility bills to prove or disprove the financial nature of their relationship.
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