Did you just immigrated to Canada or did you immigrate to Canada before?
You might received this letter from CRA that you did not respond to.
Even though it is still in the past you can still ask CRA to adjust it and they will give the money that is supposed to be yours.
There's no harm in trying, if you will get them, it will be an additional money for you.
If you have any questions, just comment below and I will try to answer your questions.
