Which province's payroll rules apply if my employee lives in Ontario but works remotely for our Quebec office?

This is a situation worth getting dedicated advice on, because Quebec is a genuinely different case from an ordinary interprovincial Ontario payroll question. Quebec administers its own provincial income tax and runs its own parallel pension plan, separate from CPP, rather than participating in the same federal collection framework that Ontario and most other provinces use — Ontario's provincial tax, by contrast, is collected by CRA under a tax collection arrangement, which is a materially different administrative setup.

Because of this, an Ontario-based employer with a remote employee connected to a Quebec office — or a Quebec-resident employee working for an Ontario company — faces a dual-system payroll compliance picture that doesn't arise with purely interprovincial Ontario arrangements. The usual "province of employment follows where the employee reports to work" concept still matters, but layering Quebec's separate tax administration and pension system on top of that makes it considerably easier to apply the wrong province's rules by default, particularly around which pension plan applies and which tax authority actually receives the remittance.

Given how different Quebec's system is from the rest of the country's, this is exactly the kind of arrangement where getting payroll-specific tax advice early is worthwhile, rather than assuming standard interprovincial rules translate directly to a Quebec-connected employee.