I don't know if this is the right platform to ask this, but I recently started a job with the federal government, but I live on the Quebec side.

I am super confused regarding taxes. Deductions done by my job go to Ontario and the Federal government, but come April 2022, I have to declare my taxes in Quebec, so there will be a discrepancy in my taxes since the tax bracket for Ontario (9.15%) is much lower than Quebec (20%).

I called Revenu Quebec for clarifications, they said that I can either put money aside ever month, and pay the difference in April, or come April I can use box# 438 on the T1 to transfer 45% of my federal deductions to Quebec, and put the same amount on box#454 on the R1.

I am confused as to why would someone pay a lump sum in April if one can just transfer the money from fed to provincial?

Am I supposed to pay the 10.85% difference myself, or is it the difference between 10.85% - (45% of fed tax transfer)? I don't know if that makes sense.

I am just trying to figure out what is the percentage difference I will have to pay come April 2022, so I can inform my employer to remove extra monthly deductions from my salary to avoid paying anything next year.

In other words, I want to know how to calculate the difference, and if I should include the 45%

I hope this is clear, thank you