Hello Anthony,
thank you for your message, which is helpful, as it points towards the right piece of code. In fact the message that can be triggered under certain circumstances is not the main point behind the variable. This variable triggers creating a new tax certification period itself (by being set to YES). Which is apparently why the dynamic action sets it in case of a re-entry action. I figure this is done because the code assumes that re-entry of an employee that used to have left the company always needs to trigger a new certification period, even if it occurs in the same fiscal year.
But this triggers infotype 12 as the first infotype in the info group in this case, which can be irritating.. Especially if the info group contains infotype 12 itself, causing this infotype to appear twice during the re-entry action dialogue.