If you separated or divorced during the tax year, the Canada Revenue Agency (CRA) will still require your ex-partner’s information. The information is needed for a number of reasons, like eligibility for certain credits or deductions, handling property you still own together, etc…

If you separated or divorced before the tax year, you would say "No" to the question "Did you separate from your spouse/partner in 20xx?". Then you won’t need to provide any info about your ex-partner.