What is your effective tax rate if you work from home in Montreal for a company in Toronto?

Question

What is your effective tax rate if you work from home in Montreal for a company in Toronto ?

Does Quebec Tax abatement of 16.5% apply ?

Answer 1

Assuming that you don't own the business, it would seem to apply. The CRA says:

If you were a resident of Quebec on December 31, 2016, and you did not have a business with a permanent establishment outside Quebec, your refundable Quebec abatement is 16.5% of the basic federal tax on line 55 of Schedule 1.

If you had income from a business (including income you received as a limited or non-active partner) and the business has a permanent establishment outside Quebec, or you were not a resident of Quebec on December 31, 2016, and the business has a permanent establishment in Quebec, use Form T2203, Provincial and Territorial Taxes for 2016 - Multiple Jurisdictions, to calculate your abatement.

For people whose income isn't coming from businesses they own, this seems quite clear.

Answer 2

For tax purposes, what matters is your province of residence at December 31st. Quebec Tax abatement therefore applies if you were living in Quebec, regardless of your employer, assuming you are an employee.

As for effective tax, your question misses some data and does not quite make sense as effective tax is the result of dividing your total taxes paid after deductions and tax credits by your total income. As such, one cannot tell you your effective tax rate without knowing taxes paid after deductions and tax credits and total income.