You might need to wait a year and see how it works out when filing your income tax return with the CRA. As you started mid-year there may be a few things that happen around tax time: - adjustment for taxes paid for a company in Manitoba while you reside in Ontario (tax rates may be different) (this happens irrespective of the partway through the year thing) - EI and CPP contributions being adjusted (due to possible overcontribution)

I haven’t done the exact math to figure out where this is happening in your case but it might be worth doing a sample tax return and seeing if you’d likely be eligible for a refund in April. The nature of how this is that employers will generally over withhold instead of under, especially partially during the year, because they don’t have visibility into your previous income or withholdings.