Hi Josh,
I was very confused with the whole tax thing when I did mine here last year. There is actually some info on the whp website now,
https://www.whpcanada.org.au/canada_gui … etaxreturn
It says this about your residency status
Step 1: Determine Your Canadian Residency Status
Most participants of International Experience Canada [link to HQ About page] are considered "non-residents" for Canadian income tax purposes. However, if you lived in Canada for more than 6 months during the taxation year, you may file your income tax return as a resident. While in Canada, call the International Tax Services Office at 1-800-267-5177 to find out if your home country has a tax treaty or agreement with Canada - this can affect your income tax status.
there is a lot more on the page. Last year I had only been over here half a year exactly and only worked two of the six months so I filed as a non-resident, but this year I have been working for the full 12 months so I am going to file as a resident. That is how I understand it, I think you can actually contact the Canada tax services office and ask them. I didn't try to claim back any excess money for anything, just the standard taxes so I don't think it made much of a difference, but if you are trying to claim certain expenses you should find out.
I would recommend talking the tax people directly, I must have asked about 5 different accountants and they all gave me different answers, so go straight to the source
Hope this helps!