To be common-law, you have to be living together in a marriage-like relationship for 1 year. I'm not sure but in your wife's situation it sounds like they were a couple many years ago... moved in together at some point.... then broke up but continued to share the same house. Is that correct?
Here the legal common-law definition gets tricky since it's all about timing. The date they were living together as a married-like couple for 1 year, is they date they would have entered the common-law relationship. The date they split up is the date the common-law relationship would have officially ended (even if they were still living together). It would be the same as if a married couple got a divorce but still lived together. So in lots of respects the actual date the breakup happens is simply whatever you say it is... since there is no "proof" you actually broke up on some particular day. So did they break up before or after living together 1 year?
Anyways it also sounds like they NEVER filed any joint taxes together as common-law. So my advice is to not mention it now. This would open a whole can of worms if the CRA ever found out they were common-law at some point in the past... but never filed taxes together.
Here the legal common-law definition gets tricky since it's all about timing. The date they were living together as a married-like couple for 1 year, is they date they would have entered the common-law relationship. The date they split up is the date the common-law relationship would have officially ended (even if they were still living together). It would be the same as if a married couple got a divorce but still lived together. So in lots of respects the actual date the breakup happens is simply whatever you say it is... since there is no "proof" you actually broke up on some particular day. So did they break up before or after living together 1 year?
Anyways it also sounds like they NEVER filed any joint taxes together as common-law. So my advice is to not mention it now. This would open a whole can of worms if the CRA ever found out they were common-law at some point in the past... but never filed taxes together.