The following information is in Operational Bulletin 480:
2.4 Assessing evidence of compliance of the two-year condition
To maintain their permanent resident status, the sponsored spouse or partner is required to cohabit in a conjugal relationship with their sponsor for a continuous period of two years after the day on which they became a permanent resident.
While the regulations require a “continuous” period of two years of cohabitation, from time to time, one or the other partner may leave the home for work or business travel or family obligations. CIC officers should follow existing guidelines when assessing a period of cohabitation where temporary or short separations have occurred. See OP 2, Section 5.35 for more information.
A conjugal relationship is interpreted as being a relationship where individuals are interdependent and have a significant degree of attachment — financially, socially, emotionally, and physically — where they share household and related responsibilities, and where they have an exclusive relationship; a mutual and continuing commitment to a shared life together. See OP 2, Section 5.35 and IP 8, Section 5.20 for more information.
The sponsored spouse or partner must provide evidence of their compliance with the condition if an officer requests such evidence because they have reason to believe that the sponsored person is not complying or has not complied with the condition (for example, when a tip is received or a CIC or a CBSA officer has information indicating non-compliance), or if requested as part of a random assessment of the overall level of compliance with the condition by the permanent residents who are or were subject to the condition.
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2.6 Processing Instructions for cases of non-compliance
CIC officers may request evidence of compliance because they have reason to believe that the sponsored spouse or partner is not complying or has not complied with the condition, or the office may request such evidence as part of a random assessment of the overall level of compliance with the condition by the permanent residents who are or were subject to it.
CIC officers may make a determination as to whether the sponsored person has failed to comply with the condition during or after the two-year condition period (s.72.4).
If the sponsored spouse or partner does not meet the condition of cohabiting in a conjugal relationship with the sponsor during the two-year conditional period and they are not eligible for an exception to the application of the condition, their permanent resident status could be revoked. An inadmissibility (44) report may be written on the basis of non-compliance with s.41 (a) of the Act and as per s.72.1 (1), as the condition imposed would not have been met. This report could be referred to the Immigration Division (ID) of the Immigration and Refugee Board (IRB) for a hearing and subsequent issuance of a removal order, if applicable.
If the removal order is issued the sponsored person may appeal the removal order before the Immigration Appeal Division (IAD) of the IRB, as per section 63(3) of the IRPA. The IAD has the authority to allow an appeal on humanitarian and compassionate grounds, which may include Best Interest of the Child (BIOC) considerations.
If the appeal is dismissed, the removal order could be enforced, permanent residence could be revoked and removal actions could be undertaken.
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So it sounds like CBSA can ask for proof (at anytime) that the couple is still living together, while at the same time, it says [sec 2.6] that non-compliance could lead to PR revocation.
Huh? If they determine that there is non-compliance why would it not be revoked?
It would certainly seem plausible that CBSA will know when the person leaves Canada and doesn't return; they must be checking for things like this for those with Condition 51.
IMHO, if the OP leaves and is living abroad and is asked to provide proof of cohabiting (which would be nearly impossible) and it does lead to revocation, that would most certainly have a negative impact on future plans to return with the new partner, right?