Gross Up Elements in Canadian Localization

Summary:

need help to understand how gross up works in Canadian localization

Content (required):

I have very inconsistent system behavior when use Gross Up elements and I can't figure out why in some cases there is an FIT and in other there is no FIT.

For example if I try to gross up 200CAD for employee - system would not add FIT but if I process these 200CAD as a non-grossed up element - there is an FIT.

For the other employee system would gross up the same 200CAD in the same pay period.

Difference between these employees is that the one that has gross up doesn't have any regular earnings from the beginning of the year, and the one who doesn't have gross up- has regular earnings.