How i do this is......I have garnishee set up in the employee master so it will show on the deductions for that employee.  I enter his/her payroll first without posting and look at the gross amount on the screen and calculate the 20% manually and then go into your deductions in the payroll entry and enter that amount.  Are you sure it is on the net amount because usually CRA wants these amounts before any taxes have been taken off?  Then there is usually a form you need to fill in and send CRA a cheque.  You cannot do it like Taxes or CPP etc. 

I was able to do it by manually entering the deduction after tax - I just wasn't sure if there was a way to set it up to do it automatically, but there does not appear to be.

And yes, it most definitely says 20% of NET pay on the CRA letter.

i Andrea, okay.  You could set it up to automatically by putting the amount in the master IF the amount doesn't change each period that you pay.  If there net changes all the time then no you have to manually enter it into the deductions.   This is the first time I have heard of CRA pulling off of the net.  Very strange!  :-)

I thought it was strange too! I wish it was a set monthly amount like every other garnishment that I've had to set up, but leave it to the gov't to always make things more difficult haha

This particular employee's hours do vary, so I guess I will have to continue to calculate and enter the deduction manually.

Thanks so much for trying to help!

Your are most welcome.