Question about the Common-Law Sponsorship

[Rob_TO]

I can do this, even if my Sin number has expired as it was only valid for 1 year which is the duration of my owp in canada?

Yes, as it would be a re-assessment of previous taxes. If neither of you were getting any benefits (like GST rebate cheques for example), and both of you made over approx $10K in income so there is no spousal tax credit claim, then it may possibly have absolutely no effect on your actual tax return numbers.

HOWEVER even if you didn't make any income in Canada in 2014, she still needs to include you as her spouse in her own taxes. Any income you made in the US ("world income" as defined by CRA) would still count towards her total family income.